The iPhone 6 might only be one generation newer than the iPhone 5S, but to look at it you'd be forgiven for thinking there were several years between the two phones. It has a larger 4.7-inch screen and a whole new look, with a thinner, curvier design.
The iPhone 6 is also more powerful, as you'd expect with a generational leap, and it has noticeably better battery life, but beneath the surface much has stayed the same. The screen for example, while bigger and higher resolution (750 x 1334), retains the same pixel density.
It has an 8MP camera, just like the iPhone 5S, albeit with some improvements to the software, and both phones now run iOS 9.2.1.
With a starting price of £459/$549/AU$929 it is of course more expensive, and if you particularly want a small screen you may favour the iPhone 5S anyway, but if you can afford the extra outlay the iPhone 6 is a better buy for most. The increased screen size really is beneficial, and the better battery life improves on one of the 5S's main issues.
The iPhone 5S isn't really in the same league as the iPhone 6S, but as a one-time Apple flagship and a still fairly expensive phone it's worth comparing them.
Like the iPhone 6, the iPhone 6S sports a different and altogether more modern design to the iPhone 5S. It's also a lot more powerful, has a new 12MP camera, a larger 4.7-inch screen, better battery life and innovative new display tech in the form of 3D Touch.
While it's not a massive jump over the iPhone 6 it's night and day compared to the iPhone 5S. Of course with all these upgrades comes a big jump in price, as the iPhone 6S starts at £539/$649/AU$1,079. You also get the option of 128GB of on-board storage.
The iPhone 6S is the best iPhone yet and worth the money, but it's significantly more expensive than the iPhone 5S, so it's not remotely budget-friendly.
Sony Xperia Z5 Compact
Few companies are making small smartphones these days, but with its Compact range Sony is still supplying them. The latest of these is the Sony Xperia Z5 Compact and despite being a lot newer and almost packing flagship specs it's actually a similar price to the iPhone 5S.
It includes a 4.6-inch 720p screen, which is larger than the one on the iPhone 5S, but still pretty small and similarly sharp at 323 pixels per inch.
It's also powerful, thanks to an octa-core Snapdragon 810 processor and 2GB of RAM. Like the iPhone 5S it has a fingerprint scanner, but its battery life is way better and it has a top of the range 23MP camera.
The design perhaps isn't quite as premium but in most other ways you're getting a lot for your money and more than the iPhone 5S can deliver. The 5S might still look like a flagship, but the Sony Xperia Z5 Compact performs like one.
Samsung Galaxy S6
Remarkably the Samsung Galaxy S6 has now come down in price so much that you can get it for little more than the iPhone 5S and really there are only two reasons not to choose Samsung's phone- you want iOS, or you want a small screen.
At 5.1 inches the Galaxy S6 doesn't have a massive display, but it's substantially larger than the 4.0-inch screen on the iPhone 5S. It's also far, far higher resolution at 1440 x 2560, so images are crystal clear.
Unlike most previous Samsung handsets the S6 is also built from premium materials, with sheets of glass enclosed in a metal frame, leaving it looking just as high end as the iPhone 5S.
There is, of course, plenty of power too, not to mention a fingerprint scanner and a great 16MP camera. Battery life isn't great, but then nor is it on the iPhone 5S.
The latest creation from Google and LG is cheaper than the iPhone 5S, and is well worth considering if you want something that's both newer and less expensive – provided Android is to your tastes, of course.
The phone features an appealing design, some upper-mid-range specs and Android 6.0 Marshmallow, with all the visual appeal of Material Design. The 5.2-inch screen runs at a resolution of 1920 x 1080 pixels.
The camera is disappointing (as they often are on Android devices), so serious photographers will favour the Apple option. That said, the iPhone 5S is likely to get retired before the Nexus 5X, which only launched last year.
You get more power for less money with the Nexus 5X, although overall a lot of people would still plump for the iPhone 5S.