Your phone is due an upgrade. Before you go straight for the new iPhone 6 or even the 6 Plus, why not look into the iPhone 5s instead? That's what I did – and I couldn't be happier.

For a while, some mobile service providers were struggling to keep up with demand for the newer models. The 6 Plus particularly suffered. Customers were waiting weeks to get their hands on the smartphone they wanted. Now the dust has settled somewhat, is the 6 really worth it?

In a report from the Kantor World Panel, looking into the market over a three-month period ending with October 2014 in the USA, the iPhone 6 dominated the period with a 33% market share. The 5s nonetheless held a very respectable 26%, while the 6 Plus held 10%.

The iPhone 5s is still a popular and respected device.

Ergonomics

iphone 6 and 6 Plus

Perhaps surprisingly enough, one of the biggest deciding factors in upgrading is size. The 6 is the largest iPhone we've seen so far, with a 4.7inch display compared with the 5s's 4inch. And the 6 Plus measures in at 5.5inch! Smartphones becoming more like tablets has been a trend for a number of years now, in both size and thickness (leading to the abhorrent term, "phablet," a halfway-house between phone and tablet).

Frankly, if I wanted a tablet, I'd buy a tablet. The iPad, for instance, is great, but if I'm taking even my iPad Mini anywhere, I'll carry it separately – in my bag or a laptop case. The mobile phone, though, was designed to be portable; instead, as they have evolved, they're beginning to revert to their more primitive sizings. Whenever photos of those early mobiles crop up, they're met with comparisons to bricks.

In our iPhone 6 Plus review, we noted that "as a portable communication device the iPhone 6 Plus falls short," so while there are those who love the larger screen, many still prefer a model that doesn't fill up your whole pocket.

The 6 also feels awkward in your hand. The average palm size for a male is 3.3inch and for a female, 2.91inch, so a larger model makes gripping harder. That's why the lock button has moved to the side on the 6, a break from previous models of the iPhone, iPod, and even iPad. And why Apple have been forced to add Reachability. To enable it, you go into Settings > General > Accessibility > Reachability, and then by lightly touching the home button twice, elements at the top of the screen will move down to within an attainable distance.

Also because of its size in comparison to the hand, the iPhone 6 Plus (and to an extent the iPhone 6) feels surprisingly slippery — the aluminium housing has little texture, so a case is advisable.

Price and Capacity

Money: the root of all evil. Apple loves it. You're probably quite partial to saving it too. On one hand, if you don't have much money, the 5s is a great option; on the other, even if you have money, is there much point in shedding out extra cash just to keep up with the Joneses?

Apple is known for its high price points, and the 6 is no different. But the 5s was only released in September 2013, just one year before its successor, so it's an affordable way of obtaining a modern smartphone without spending the entire month's wages.

The base 16GB iPhone 6 starts at $199 on contract, or an extra $100 for the 6 Plus; without a contract, a 6 will set you back $649. A 16GB 5s costs $99 with contract, or $549 without, or a 32GB one is just $50 extra. There is no comparison for the latter capacity, as Apple did something a bit surprising: odds were that the 16GB would disappear, but actually neither the 6 nor the 6 Plus come with 32GB; instead, they're only available with 16GB, 64GB, or a massive 128GB. It's a bizarre choice, one likely made to force customers to spend more on the bigger phone. When upgrading, people typically look to either keep the same capacity or get a slightly bigger one, not downgrade to 16GB. In fact, Iterative Path reckons this move earned $4billion.

Your choice of iPhone 5s is limited to either 16GB or 32GB via the Apple store now, but the 64GB is still around on sites like eBay. A second-hand 16GB 5s can be picked up for as little as $150, or generally about $300; the 16GB iPhone 6 typically sells for about $500.

iPhone Cases

Aside from initial purchase, accessories for the 5/5s are generally cheaper, and at the moment, there are more extras on the market for the older model, especially when it comes to cases. Yes, there are ample cases for the 6 and 6 Plus, but they are a bit plain, with not so many great specialist items like ultra-tough cases.

Smartphones are an extension of our personalities, after all. We should be proud to display interests, hobbies, or geek credentials! If you're looking for a personalised case, the Internet boasts a wealth of services that can help you design your own – including Casetagram, which turns your Instagram photos into a snap-on case.

Features and Functionality

Admittedly, the iPhone 6 has a number of improvements over its predecessor. The 5s is slightly older, but does that make much of a difference?

Notably, the 6 has an A8 processor, which is faster and more efficient resulting in a longer battery life. The M8 co-processor, too, has upgraded the phone's ability to collect sensor data – so we're expecting an influx of sporting apps. However, the 5s' A7 remains a highly-efficient processor, more than capable of dealing with anything the App Store throws at it.

Apple Pay is one thing that the 6 and 6 Plus are capable of, but the 5s isn't. Apple Pay uses near-field communications (NFC) technology, a secure element (SE) chip, and Touch ID to pay for items in the same way as "tap and go" or "contactless" credit cards. While the 5s has Touch ID, the NFC and SE chips are absent. It's only just got going, but already Apple has had to blame banks for fraudulent activity, insisting that Apple Pay is "extremely secure."

And then there's the added problem with Apple Pay: it doesn't (yet) work outside the USA. But if you are looking for contactless payment, most bank cards are capable of that already. This new gimmick isn't going to change the world.

The iPhone 6's camera is an improvement on the 5s... but not vastly. Both have Dual LED Flash, a 29mm focal length, and 1.2 megapixel forward facing camera. Apple, though, has added better digital image stabilisation, face detection, and low-light photography; while in camcorder mode, the 6 and 6 Plus also has increased frames per second and slow-motion recording. The 5s has this latter feature, but recording 120fps instead of the 6's 240fps. It is an impressive camera, but perhaps isn't the leap forward some Apple enthusiasts were expecting, especially considering the noticeable leap in camera quality between the 5 and 5s.

5s-6 comparison

The 5s' 1.9µm pixels means it's better capturing panoramas and low-light images than the 5, as well as Burst Mode for still photos and the aforementioned slo-mo camcorder. Its 'True Tone' flash also boasts a more natural light to proceedings, while its 1.5µm pixel back camera captures more detail.

Problems With The 6 and 6 Plus

As with most cutting-edge technology, the iPhone 6 and 6 Plus have their fair share of issues.

Complaints have concerned a gap between the screen and aluminium in which hair gets caught and ripped out; inconsistent backlighting; capricious reboots; the screen becoming easily scratched; and the camera's occasional inability to focus. One particularly infuriating problem - which, again, Apple denies, instead saying it's an isolated incident - involves the screen locking completely when shutting down apps, the white screen of death when accessing messages, and persistent instructions to sign into iCloud (followed by an inability to do so).

Which Will You Choose?

Yes, much of this comes down to personal taste. But the iPhone 5s, 6, and 6 Plus are all great smartphones.

With just a year between them, the core differences seem to be size, price, and Apple Pay. Technically, the 5s is already old. And, if reports of the next iPhone coming out later this year are true, the 6 and 6 Plus will be too.

Which one do you prefer? Are you having problems with either? What's the deciding factor for you? Most importantly: are the 6 and 6 Plus just too big?! Let us know below.