I have come from an iPhone, and previously used a Galaxy S4, HTC One and Note 3
1. Build quality - lovely. Samsung needs to leave iPhone 3 style and plastic fantastic. HTC is also very nice - difference is a taste thing
2. Screen. Excellent. Can't really comment. Samsung looks more 3D but also more weird. Sony is somehow more crisp.
3. Takes an SD card - yay!
4. Buttons really nicely placed
5. A photo button - Sony's camera division makes itself know
6. Sony software is non-intrusive
7. Mostly weather proof
8. Battery capacity significantly higher (3200 vs 2800&2800). However S5 does have a removable battery
9. On switch on the side (not the top which is a pain) and can set the phone to have a double tap to switch on, which is great
Galaxy S5 looks and feel disappointing, still plastic fantastic.
HTC One M8 very nice. Not much in it. Prefer the more military look of the Z2
It was also nice to get a screen protector in the box. A small thing I know but useful.
Development points ? have to say something to sound honest but really can't think of much. The door covering the charger point looks a bit flimsy. understand its needed for the water proofing but lets see how it goes. Would like a numeric line of keys in default keyboard. Could someone also make a dock that can be used with the a case on!!! Some silly extras, like a 4k res screen but I guess this will happen at sometime in the future
Perhaps the top phones are so good these days that its all down to taste really, but the keyboard is good on the Z2 and I feel, along with the Note 3, that Android has finally answered the usability of the iPhone but with much enhanced functionality.