You can upload iTunes music to Google music and have it in the cloud so that's not much of an issue. You can then download it to the phone via wifi when required. (Works on iOS and Android)
5S camera is still pretty good but the SE is better (2 generations newer than the 5S)
Plenty of good Android phones about.
Probably easiest to narrow it down with budget and max screen size
The newest Motorola G4 is getting great reviews and starts at £160.
Nexus 5x and 6p are both very nice.
The new oneplus 3 sounds good.
The Samsung, HTC and LG flagships are all good too but are up with the iPhones in terms of cost