When buying a laptop or desktop, it's easy to get sucked into processor and RAM upgrades. However, no slight CPU boost improves day-to-day performance as much as switching from a slow hard drive to a fast SSD.

Unless you spend an awful lot of money, though, an SSD will not leave you with much spare space. A 1TB hard drive can costs a little as £40, a 1TB SSD around £240.

An external hard drive is, for many, the best solution. You can offload your data from your MacBook's SSD or your iMac's Fusion drive when it fills up, or keep one plugged in 24/7 as a store for any non-performance-critical data. A hard drive is perfect for music, video files and photos.

To find the best hard drive for your needs, you need to answer a few questions.

How much storage do I need?

Hard drive storage is relatively cheap. Unless you are really out to save your pennies, the smallest size of hard drive we'd recommend is 1TB.

Upgrades to 2TB, 3TB and even 4TB are also cost-effective, often making the bump up to the next model a good idea. Each terabyte can store around 11,000 music albums at 192kbps quality, but such storage doesn't seem so grand when you start archiving 4K video.

1GB of data will store as little as three minutes of 4K video shot with an iPhone 8.

Unless you're happy to have a digital bonfire every year, you also need to consider your future use. We'll use more data in the coming years, not less.

Portable or desktop?

If you think you'll be happy with a 1-4TB hard drive, you can buy a portable drive. These use small 2.5in disks, and as such they fit happily into a coat pocket.

They are usually bus-powered too. This means you just need to plug them into your desktop or laptop, no separate power supply required. There's just one cable, and the drive will barely take up any space.

If only an ultra-high capacity hard drive will do, consider a desktop unit. These use larger 3.5in drives, and tend to cover capacities from 4TB to 12TB.

They'll need to be plugged in for power. That's fine if they'll stay at home 95 per cent of the time, but they are not portable.

Ruggedisation

The choice is clear for those after a drive that can be connected anywhere. You need a 2.5in portable model.

Some of these also offer ruggedisation. Shock protection is the most important kind for a hard drive, as unlike an SSD they have moving parts that can be permanently damaged following a drop.

Rugged drives usually have some form of rubber coating that soaks up impact force, and a toughened enclosure that won't dent, crack or collapse under any normal amount of pressure.

A few also have water resistance. While few are rated IP67 like an iPhone X, meaning they can be submerged in water without damage, several can handle rain or water jets/splashes.

What extra features do you need?

Buy a larger drive, though, and you're more likely to get other features. Desktop units may have a built-in "hub", letting you plug in memory cards or peripherals using USB ports.

These are particularly useful if your current setup has limited connectivity, or the USBs you do have just aren't that handy.

Matching the hard drive's connector to those of your laptop is desktop is also essential. You'll get a cable in the box, but it will either terminate with a USB or USB-C shaped plug.

If you have an older MacBook, you'll want the older USB type. A USB-C connector is essential if you own a recent MacBook.

Not all USB-Cs are the same, though. MacBooks support Thunderbolt 3, which has eight times the bandwidth of USB 3.0.

However, in most cases you don't need to worry too much whether a hard drive uses USB 3.0 or Thunderbolt. The disks themselves just aren't quick enough to break through the data speed limits of normal USB 3.0.

Wireless and NAS

Aside from one special wireless hard drive from Western Digital, below you'll find predominantly "normal" external hard drives. There's another category you may want to consider too: a NAS.

These network-attached storage drives connect to your home Wi-Fi to share their data with other devices in your home. That might be a smart TV, Apple TV, a tablet or laptop.

A NAS is particularly useful if you want to set up a media server at home. This is like a wireless jukebox you can fill with videos, photos and music. Read our best NAS drives feature for more.

1. Seagate Backup Plus Hub

Seagate Backup Plus Hub

This one is the best for high-capacity home storage (and also the best overall).

Desktop-style hard drives may not seem that appealing when relatively high-capacity ones that fit in a pocket are affordable. However, there's still a real appeal to them particularly if they are never, or rarely, going to leave the office.

The Seagate Backup Plus Hub is a classic 3.5in desktop drive. It is available in sizes up to 10TB, and we're using this ultra-high capacity version. There's no difference in physical size between these variants, though.

It's 198mm deep, 118mm tall and 41mm deep, so not much larger than the 3.5in drive inside. The Seagate Backup Plus Hub does not have remotely Mac-like styling (although that is less true of the white, specifically Mac-focused model we will discuss in a moment) but there are some touches worth noticing. The sides are glossy black, the top, bottom and back a heat-dispersing honeycomb that looks fairly good.

A sloped front also stops it from looking like a plain plastic brick.

There are a few practical unique selling points too. The Seagate Backup Plus Hub has two powered USB 3.0 ports on its front. Place the drive intelligently in your setup and these could become the most convenient ports in your office.

You could use them to charge your phone or tablet.

The Seagate Backup Plus Hub is also designed to be used with both Windows and Mac OS computers. It is formatted using the NTFS file system, the standard for higher-capacity Windows drives. Just run the Mac user file pre-loaded on the drive and it'll install a driver that lets you write to the drive using OS X.

You can read a Windows-formatted drive with a Mac, but not normally write files to it. If you don't have both systems, though, you might as well reformat the Seagate Backup Hub Pro using OS X's Disk Utility app. It only takes a minute.

(The Mac version of the hard drive is formatted for Mac by default but you can download a Windows driver.)

This is a relatively long-standing model in the Seagate line-up, so it doesn't have a connection designed for Thunderbolt or USB-C 3.1 ports. A microUSB 3.0 socket sits on the back, which looks like a normal microUSB with a little sibling attached. The 1.2m cable ends in a normal USB port, perfect for older Macs.

You might expect lesser performance from a non-Thunderbolt drive, but the Seagate Backup Hub Pro 10TB's speed is excellent. There's a Seagate Barracuda Pro drive inside, which costs more than this drive when bought alone. Makes no sense, right?

It writes at up to 197MB/s and reads at an excellent 264MB/s. This is far better than the speed of a rival 2.5in HDD.

However, it also likely explains why the 10TB Seagate Backup Hub Pro is significantly more expensive than the 8TB version.

2. LaCie Rugged Secure

LaCie Rugged Secure

This one is the best for travellers.

Hard drives are not easy to make rugged. They need ports. And as they use moving elements, spinning platters, they can easily be damaged by impact force.

LaCie makes the most recognisable rugged hard drive around. The LaCie Rugged Secure has a tough aluminium drive enclosure and an outer orange rubber buffer that soaks up the force of any drops. You'll often see these marketed as drives for creative professionals who work out in the field, but they're just as useful for anyone after a drive that is both portable and tough.

Don't want the bulk of the rubber outer? Most online images don't make this clear but you can actually take this part off. It leaves you with a slim, severe-looking 2.5in drive.

LaCie makes a handful of different drives in this rugged line, but the Secure is one of the most accessible. It isn't too expensive and has a simple USB-C port. It can plug into USB-C ports with or without Thunderbolt 3, or the full-size USBs of older Macs and MacBooks with the right cable.

One is not included in the box, though, and the USB-C cable you do get is very short, roughly 30cm. It makes sense for a largely portable model, but is worth considering if you'll primarily use the LaCie Rugged in a home office. LaCie likely envisions these drives spending a lot of time in rucksacks and flight cases.

So how rugged are they? There's more to it than just the impact protection of the rubber outer. The thick, rectangular housing inside is designed to withstand being rolled over by a 1-ton car, like a Nissan Micra.

Unlike some of the bigger models in the range, the Rugged Mini does not have an IP-rating, the industry standard for water and dust resistance. However, LaCie does say it can handle rain.

This suggests that, like phones, the USB-C port on the rear is reasonably water-resistant by design. When the drive is seeking you'll see an LED light up through the orange rubber by this socket.

The drive performs exactly as expected, matching the speeds you'll get from other 2.5in drives. We see read speeds of 133MB/s and writes of 131MB/s. This is effectively dead on LaCie's own claims of 130MB/s.

Transferring a 2GB video files takes 16 seconds. We're miles off even entry-level SSD speed here, but even with a premium rugged design the cost-per-gigabyte is far lower than any SSD.

We're looking at the Secure version of the Rugged, which comes with software that lets you encrypt the entire drive with a password, mirror folders on another drive and recover files easily from backups. You also get two years of Seagate's data recovery service, which is effectively an advanced warranty in case anything goes wrong.

Happy with a more basic rugged drive? There are cheaper versions without these extras.

3. Toshiba Canvio Premium for Mac

Toshiba Canvio Premium for Mac

This one is the best for MacBook owners.

Most portable hard drives are made for Windows. It shouldn't put off any but the most technophobic Mac owners, but the Toshiba Canvio Premium for Mac is a true plug and play drive.

This means it is already formatted to the Mac OS Extended file system. You can start dragging and dropping files right away.

The Toshiba Canvio Premium for Mac design also complements a MacBook nicely. Its top is anodised aluminium, with just a slightly less fine finish than a MacBook keyboard surround.

You're not going to convince anyone this is an Apple product, though. The Toshiba logo is embossed into the top, and the silvery sides and black underside are plastic, not metal.

Both the 1TB and 2TB versions are an ultra-slim 13.5mm thick, but the 3TB we have here is 19mm thick. The £25 or so you'll pay for the extra gigabyte is a sound deal, but portability is a shade worse.

However, the Toshiba Canvio Premium for Mac does have a touch of class missing from the all-plastic drives common in this price band. There's also a blue LED under the little circle on the top. Whether that's a positive or negative depends on whether you find HDD activity lights distracting or not.

The tricky challenge for a drive like the Toshiba Canvio Premium for Mac is how to cater for both new and older Macs. It needs to be able to plug into both USB and USB-C shaped ports.

Toshiba includes a little USB-C adapter rather than bundling two cables. Full-size USB is the default.

This, of course, means the Toshiba Canvio Premium for Mac is a USB 3.0 drive rather than a Thunderbolt 3 one. The max bandwidth is 5Gbps (625MB/s) rather than 50Gbps (5000MB/s).

While this sounds like a huge difference, it is not a functionally significant one because of the limits of the drive inside. It's a standard 2.5in 5400rpm hard disk with real-world sustained read and write speeds of up to 133MB/s. USB 3.0 is simply not a bottleneck.

This is the same speed you'll see in other high-quality ultra-portable drives, matching the LaCie Rugged. If you will juggle dozens of gigabytes of data regularly, the obvious upgrade is to an SSD, not a slightly more expensive HDD.

The Toshiba Canvio Premium for Mac comes with a little extra security program too. It's Toshiba's HDD Password Tool.

This is a very simple, but dangerously powerful, app that lets you password protect the entire drive's contents. It's useful if you need to keep sensitive work or personal data on the drive, just don't forget that password. You also don't have the option to secure select folders either. It's the whole drive or nothing.

The Toshiba Canvio Premium for Mac is fundamentally similar to the Canvio Advance, a slightly cheaper drive configured for Windows. However, it's only a few pounds or dollars more, and that also gets you the higher-end look and feel of the aluminium top plate. And a neat little fabric carry case.

4. WD My Passport Wireless Pro

WD My Passport Wireless Pro

This is the best for home entertainment & photographers.

It's also perhaps the most interesting drive on test here. You can use the WD My Passport Wireless Pro like a standard wired hard drive, but it also has integrated Wi-Fi and a 10-hour battery.

A thoroughly modern drive, it's setup using a mobile app (for iOS and Android) rather than a laptop. This teaches the WD Wireless Pro your home Wi-Fi network's login so it can become part of your home network.

Within a few minutes it'll appear as a shared network drive, accessible from your MacBook and other connected devices, such as smart TVs. You can view stored videos and photos directly from your phone, again using the app to access them.

Like other smart devices of this ilk, the app is both a strength and a weakness. It allows actions not possible with the average portable hard drive but does crash on occasion.

We like it most as a drive attached to a main laptop or desktop that can be accessed throughout the house without any extra setup involved. It can also be used to backup data wirelessly while out and about, connecting directly to the Wi-Fi networks the WD Wireless Pro transmits. It creates both 2.4GHz and 5GHz (ac) hotspots.

The WD Wireless Pro is great for versatility and convenience, but performance is not best-in-class. When connected with the cable it both reads and writes at up to 110MB/s, around 20MB/s less than the best-performing affordable 2.5in drives.

Also, transfer rates are naturally much slower when backing-up wirelessly. Using the drive's 5GHz band you can expect rates of around 20MB/s. It's a perfectly sound speed if you need to ferry over a few hundred megabytes of data. But if you want to transfer a fistful of gigabytes, plugging the drive in is a better idea.

It has a few extra features, though. The WD Wireless Pro has an SD card slot one side. It's a great way for photographers to back-up files quickly out in the field.

There's a multi-purpose 4-LED array on the top too. This shows how much battery left, or how close a file transfer is to being complete.

To recharge the battery you plug the WD Wireless Pro in using the full-size USB port on the back. A smartphone-style power brick is included in the box.

The drive is, predictably, a lot larger than a standard portable hard drive because of all the extra tech required. Its footprint covers about twice the area of an ultra-portable alternative, and it's roughly 20 per cent thicker than a 3TB portable drive.

However, the WD Wireless Pro is still much smaller than a 3.5in external drive and it will fit into a small bag of rucksack with ease. Don't treat it too poorly, though, as it's an all-plastic enclosure with no official ruggedisation.

Remember to switch it off when you're done too as it will otherwise stay active until the battery runs dry. After a few hours' use the WD Wireless Pro's underside feels a little warm, which is no surprise when there is no fan inside.

5. LaCie 2big Dock Thunderbolt 3

LaCie 2big Dock Thunderbolt 3

This is the best for professionals and video editors.

The LaCie 2big Dock Thunderbolt 3 is much more than just a hard drive. To start, it contains two drives, not just one. We are using the top-end config, which has two 10TB IronWolf Pro disks, designed to handle 300TB a year workloads.

They are enterprise class drives a cut above those you'd buy in a high street electronics shop. It instantly earns extra points for reliability.

Using such high-quality drives in a smart enclosure also lets the LaCie 2big Dock Thunderbolt 3 reach SSD-like speeds when reading and writing large files. We've recorded read speeds of 495MB/s and write speeds of 487MB/s, four times the speed of a standard external drive.

While that still looks slow next to the fastest M.2 SSDs, which can read at around 3500MB/s and write at 2100MB/s, it really isn't that much slower than the ~500MB/s SSDs used in most external drives. And 20TB's worth of SSD storage will currently cost you at least £4000.

Suddenly the LaCie 2big Dock Thunderbolt 3 20TB's £900-1000 price doesn't look so steep.

This isn't a NAS drive or a miniature server box, but it does have several important additional features. A simple LaCie application lets you switch to a RAID 1 setup, where the same data is written to the two drives simultaneously to protect against data loss. This also roughly halves the write speed, though.

You have to choose between great performance and good reliability, or great backup reliability and speed that is simply very good for an HDD.

Either way, the LaCie 2big Dock Thunderbolt 3 looks great next to an iMac. It has an all-aluminium enclosure and a light-up eyeball on the front that glows blue, or red when something has gone terribly wrong.

You're unlikely to encounter too many issues, though, because while this is a high-end unit it still has the simplicity of a consumer product. For example, you can just pull at the aluminium blocks at the front to open-up the drive bays, no cables involved.

The LaCie 2big Dock Thunderbolt 3's connectivity is comprehensive too. There's a 5Gbps USB-C port on the back, and two Thunderbolt 3s. This lets you daisy chain multiple drives.

There's even a full-size DisplayPort, which can pass through the video feed from a connected MacBook to a monitor. This introduces the other side of the 2big's personality, that of a dock.

USB 3.0, SD and CompactFlash connectors sit on the front, particularly useful for photographers.

Any complaints? As the IronWolf Pro drives inside run much hotter than most, the LaCie 2big Dock Thunderbolt 3 uses a fan that sits at the back. This is not a silent box, but the high-quality, low-noise Noctua fan is actually the least noticeable part. The operational noise of the drives themselves is more evident than that of a lower-performance 2.5in drive.

We don't think this is a big issue, but is something to bear in mind if you're looking to plug into an often virtually silent MacBook.