It's been more than six months since Apple introduced the iPhone 5s and the iPhone 5c in September, at the expense of the iPhone 5 which was dropped from the line-up. The two new iPhones proved to be very popular upon launch, with most Apple Stores and carriers running out of the iPhone 5s by lunch time on launch day.

Six months on, both the iPhone 5s and iPhone 5c remain excellent smartphones with impressive specs, but it's only natural for potential customers to start wondering whether it's worth waiting for Apple's next iPhone, dubbed iPhone 6, before upgrading.

Here, we help you decide whether to buy one of Apple's current iPhones now or hold off for the next iPhone that Apple has got up its sleeve.

Wondering whether to buy a Samsung Galaxy S5? Read our comparison review of the iPhone 5s and Galaxy S5.

Should I buy the iPhone 5s?

The iPhone 5s is Apple's flagship iPhone, and therefore the best iPhone available in terms of specs and features. It boasts the speedy A7 chip and the new M7 processor, has a Touch ID fingerprint sensor built into the Home button to allow you to access the device using just your fingertips, an impressive 8-megapixel camera with larger pixels that mean better low-light results, a dual-LED flash and an all-new Gold colour option.

You can find out more about the iPhone 5s new camera features here.

Overall, the iPhone 5s is an excellent smartphone, and we wrote in our review that it's the only smartphone worth getting excited about. That is, of course, until the iPhone 6 arrives later this year. We expect that the iPhone 6 will have an all-new design (possibly slimmer and lighter than the iPhone 5s) as well as processor and camera improvements and more.

How long will I have to wait for the iPhone 6?

There's the catch. If you want to hold out for the iPhone 6 you've probably got a good six months left to wait. Most iPhone 5s contracts last for 24 months, so you won't want to buy an iPhone 5s now and upgrade to the iPhone 6 when it comes out later.

Current predictions suggest a September launch for the iPhone 6, although there are some theories that the next iPhone could arrive as early as June at Apple's WWDC event. We wouldn't hold out much hope for that one, though. We expect you're looking at a significant wait time for the iPhone 6, so if time is your priority here and you need a new iPhone within the next month or two, it'll have to be one of Apple's current iPhones.

However, if you're not in a rush we think it's absolutely worth waiting, as you can expect a significant update with the next iPhone. There's also talk of a bigger iPhone, which we know will catch the attention of many potential customers trying to make the decision about whether to buy an iPhone. Find out more about what to expect from the next iPhone in our iPhone 6 rumour round-up. Alternatively, watch the video below to discover what we think the iPhone 6 will be like.

Of course, there's always the question of money. Right now, Apple's iPhone 5s will set you back at least £549 if you buy it SIM-free from Apple's website, and is quite costly on most contracts. When the iPhone 6 launches, the iPhone 5s could become significantly cheaper, so that factor could help you decide whether to buy now or wait.

Apple traditionally drops the price of its older iPhones, though when the iPhone 5s came out the iPhone 5 was ditched completely, so it's possible that Apple will decide to do the same with the iPhone 5s when a new model comes along. The main reason Apple decided to stop selling the iPhone 5 was to make room for the iPhone 5c, Apple's (marginally) cheaper iPhone.

Should I buy the iPhone 5c?

The colourful iPhone 5c is Apple's plastic-backed mid-range iPhone, which starts at £469. It has pretty much the same internal components as the iPhone 5 did. It has the same A6 processor as the iPhone 5, the same 4in Retina display, the same cameras, and the Lightning connector. The only real internal differences between the two models are the WiFi and cellular hardware, which the iPhone 5c shares with the iPhone 5s rather than the iPhone 5. This means that better 3G signal, and it also mean better 4G compatibility.

This has led to speculation about what 2014 holds for Apple's iPhone line. Will Apple launch an iPhone 6c? If yes, will the iPhone 6c replace both the iPhone 5c and the iPhone 5s? One theory is that the internal components of the iPhone 5s will be placed inside a plastic chassis like the iPhone 5c's to become Apple's new mid-range iPhone when the iPhone 6 comes out, and this could mean the end of the road for the iPhone 5s.

What about the iPhone 4S?

The iPhone 4S is still available to buy from Apple for £349, but you'll only be able to get an 8GB model of the older device.

It's worth noting that several of the Macworld UK team are still using the iPhone 4S and are perfectly content with its features and camera capabilities. Here's our recently updated review of the iPhone 4S, which should help you make your decision.

We'd advise opting for the iPhone 5s or iPhone 5c, though, as Apple will likely soon stop supporting the iPhone 4S. Plus, the iPhone 4S still has a 30-pin connector rather than the new Lightning standard, so many new accessories won't be compatible.

The conclusion

There are several factors to consider when making your decision about whether to buy an iPhone 5c or iPhone 5s or wait for the iPhone 6.

The first is urgency. If you need a new iPhone now, you'll have no choice but to opt for the iPhone 5s or iPhone 5c. Which of those you choose depends on budget and personal preference. Our iPhone 5s vs iPhone 5c comparison review will help you there.

The second is budget. If you're after an iPhone that'll set you back less than £500 you'll need to choose between the iPhone 5c or iPhone 4S or waiting for the iPhone 6 launch to spark an iPhone 5s price drop. Don't forget, though, that you risk missing out on the iPhone 5s all together, as Apple could well decide to drop the iPhone 5s from its lineup.

The final factor, and perhaps the most important, is features. You can expect Apple to introduce exciting new features with the iPhone 6, and probably a stunning new design too, so if you want to have the latest tech to show off to friends and colleagues then waiting those six months for the new iPhone will absolutely be worth it. Particularly if you're looking for a bigger smartphone - we'd be surprised if one didn't emerge from Apple this year.

For a comparison of Apple's current iPhones, watch the video below.

Wondering how the iPhone compares to the rest of the industry? Read: How does the iPhone 5s compare to Samsung and other smartphones.

The Complete Guide to the iPhone 5s & 5c is on-sale now. Click here for buying information.