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Apple has introduced the iPhone 5S, and iPhone 5C, discontinued the iPhone 5 and left the iPhone 4S on sale. Asking yourself 'Which iPhone Should I buy?', read our iPhone 4S vs iPhone 5C vs iPhone 5S comparison to find out.

We're comparing different generations and models of iPhone that are still on sale from Apple so it's not a case of which is the best iPhone – that's the iPhone 5S – it's a case of finding out which is the right iPhone for you. See also: Apple iPhone 5S review - hands on.

The answer will depend on how much you want you spend, your personal taste and your requirements so read on to find out.

See also: iPhone 5C vs iPhone 5S comparison review: what's the difference between iPhone 5C and iPhone 5S?

iPhone 4S iPhone 5 vs iPhone 5S: Price (UK)

Pricing is quite varied across the iPhone range now. The iPhone 4S is the budget option at under £349 and the iPhone 5S reaches above £700. Meanwhile the iPhone 5C sits in the middle but is by no means cheap.

We don't know how much you've got to spend so check out the table below for full iPhone pricing details. See also: Apple iPhone 5C vs iPhone 5 comparison review: What's the plastic iPhone 5C got?

In our opinion £350 is a lot to spend on the 4S - a two-year old phone with just 8 GB of storage - so will be much better off opting for one of the newer models.

See also: iPhone 5C up for pre-order: Full UK network pricing.

iPhone 4S iPhone 5 vs iPhone 5S: Design and build

The iPhone 4S is the smallest iPhone on offer with its 3.5 in screen. However, it's the thickest and heaviest. All the iPhones looks similar but there have never been more colours on offer from Apple. The iPhone 4S comes in the classic black or white, the iPhone 5S effectively adds gold into the mix and the iPhone 5C is new territory for Apple with five brightly coloured designs. See also: Apple iPhone 5C review - hands-on.

A key difference which you'll want to consider is the material used for the casing. The iPhone 4S and 5S both use a combination of glass and aluminium while the iPhone 5C uses a one-piece polycarbonate plastic shell.

It's really going to come down to taste here so check out all the details below. See also: Apple iPhone 5S vs iPhone 5 comparison review: What's the new iPhone got?

iPhone 4S iPhone 5 vs iPhone 5S: Screen

The iPhone 4S was the last of Apple's smartphones to use the original 3.5 in screen size. The iPhone 5C and 5S use the 4 in display introduced with the iPhone 5 so that extra real-estate comes in handy. With the capabilities of smartphones and the wealth of apps optimised for the 4 in display, 3.5 in just seems too small for us now.

In terms of resolution, all the three iPhones have the same Retina quality pixel density. The key difference is the size here.

iPhone 4S iPhone 5 vs iPhone 5S: Processor

With each iPhone model on offer from Apple, you get a newer generation of processor. In theory this means performance will be better as you go higher up the range – up to 2x for each jump. We've not found any of the iPhones to suffer from any performance issues, but it remains to be seen how well the iPhone 4S will run iOS 7 and future apps so there is a risk if you go for this model.

The iPhone 5S is the first iPhone, and smartphone, to come with a 64-bit processor. This is more a marketing tool than anything at the moment but does at least future proof the device. The M7 motion co-processor is designed to make the iPhone more efficient but Apple quotes the same battery life statistics as the iPhone 5C. See below.

iPhone 4S iPhone 5 vs iPhone 5S: Storage

Like the price, storage is quite varied across the iPhone range. You get increasingly more options as you go up the models but this obviously costs more. None of the iPhones have a microSD card slot so, as usual, choosing your capacity wisely is critical. See below for all the storage options.

iPhone 4S iPhone 5 vs iPhone 5S: Cameras

If you're into photography of the smartphone variety then your photos and video are going to be better as you go up the iPhone range. All models have the same 8 Mp iSight camera but with increasingly better components and features.

For example the iPhone 5C has a sapphire crystal lens cover which the 4S doesn't have and the iPhone 5S adds a larger aperture, larger pixels and a dual True Tone flash into the mix. It also exclusively has the new burst mode and Slo-mo video.

The iPhone 5S and 5C have a far superior front facing FaceTime HD camera compared to the iPhone 4S' VGA quality snapper.

iPhone 4S iPhone 5 vs iPhone 5S: Connectivity and 4G support

All the available iPhones still has the same combination of dual-band Wi-Fi, Bluetooth 4.0 and GPS. Apple has decided not to add NFC for the new models.

However, key differences between the iPhone 4S and the two new iPhone models include the Lightning connector and support for 4G networks in the UK. The SIM-card size is less of a problem.

iPhone 4S iPhone 5 vs iPhone 5S: Software

All of the iPhones will come pre-loaded with iOS 7 if you buy from Apple so on the surface it seems like there's no difference here. However, not all of the features of iOS 7 will reach all the models.

For starters, Touch ID is limited to the iPhone 5S because it's the only one with the associated hardware (see below).

See also: iOS 7 release date, new features, which iPhones, iPods, iPads get it.

Other than Touch ID, the iPhone 5S and iPhone 5C are on a par when it comes to included software features. However, as far as Apple has detailed, Air Drop and Filters in Camera won't reach the iPhone 4S.

iPhone 4S iPhone 5 vs iPhone 5S: Touch ID

We've given Touch ID a section of its own here as it's a major and key feature of the iPhone 5S which the iPhone 4S and iPhone 5C don't possess.  Integrated into the home button on the iPhone 5S is a fingerprint scanner which can be used to unlock the iPhone instead of a passcode. It can also be used to authenticate your Apple ID.

It's a feature which might sway to towards getting the iPhone 5S over the other models.

iPhone 4S iPhone 5 vs iPhone 5S: Battery life

Battery life is similar across the iPhones on sale now. The iPhone 5S and iPhone 5C have more potential but there's been no breakthrough. It's highly likely that, no matter which model you choose, you'll have to charge it every night. See below for Apple's figures.

Follow Chris Martin and @PCAdvisor on Twitter.