It's been more than six months since Apple released its iPhone 5S, and in that time some of the company's main competitors, including Samsung, HTC and Sony, have launched new versions of their flagship smartphones too. While there are many features boasted by the iPhone 5s that those rivals don't have, they each also offer something that complete Apple's iPhone lacks, but perhaps that'll be remedied by the iPhone 6.

Here, we've rounded up some of the most interesting and innovative new features from those rival smartphones, which include the Samsung Galaxy S5, HTC One M8 and Sony Xperia Z2, that we think would be welcome in the iPhone 6. Of course, we're sure that Apple will also introduce advanced features that trump its rivals, too.

Watch our video where we compare the iPhone 5s to the HTC One M8:

Dust & Water Resistant

Samsung's Galaxy S5 is among the latest smartphones to come with an certification that deems it resistant to dust and liquids. The Sony Xperia Z2 also boasts an IP55/IP58 rating making it water- and dust-proof.

We'd love the iPhone 6 to be more durable, so if Apple is able to introduce some protection against dust and water for its next smartphones we think it will please many Apple fans.

Refocusable photos

The just-announced HTC One M8 comes with a new camera feature called UFocus, which lets you choose where you want the focus of your image to be after you've taken it, a bit like the Lytro camera.

As we've speculated in our iPhone 6 rumour round-up, it's likely that Apple will make some improvements to its camera through new features rather than an increase in megapixels, so a refocusing tool like HTCs could be one of the new features in store.

Nokia also offers a similar feature for all Lumia smartphones through the Nokia Refocus app, while Samsung's Galaxy S5 has a selective focus mode that works as you're taking the photograph rather than after it's been captured.

Late last year, Apple filed a patent that covers a refocusable camera feature, so there's no doubt that it's an idea that the company is interested in.

Power saving mode

Another Apple patent that was discovered just this month covers a battery power management system that could be used to help prolong the battery life of the iPhone 6. It works by monitoring usage trends and using that information to predict what the user will be doing, enabling it to automatically dim the screen or slow the CPU clock speed, for example, to reduce unnecessary power consumption.

Samsung, Sony and HTC each have power saving modes that help their smartphones last longer on one charge, so we're hoping that Apple will do something similar for the iPhone 6 to help us prolong its battery life.

More RAM

Sony's Xperia Z2 comes with a whopping 3G of RAM, while the iPhone 5s sports just 1GB. We'd like to see Apple boost the RAM with the iPhone 6, helping to make the smartphone more speedy and smooth to use than its predecessor.

Bigger screen

As we've noted elsewhere, pretty much all of Apple's closest rivals have released smartphones with bigger screens. While we're not hoping for a full-blown 'phablet' from Apple (that's half way between a smartphone and tablet, in case you're wondering), we would like to see a significantly bigger screen for the iPhone 6.

Front-facing speakers

Another feature from the HTC One M8 is Boomsound, which means good-quality audio from the smartphone itself. This is achieved by dual front facing stereo speakers, built-in amps and software features.

The speakers on the iPhone 5s are situated on the bottom of the device, but moving them to the front would mean a better audio experience when watching movies or listening to music.