On O2 - £26 a month contract, unlimited calls, texts, and 1Gig of data
1. Samsung Galaxy S3 - £299
2. HTC One X £199
3. Nokia Lumia 920 - Not Available
4. Sony Experia S £199
To debunc the Fandroid myth. iPhone 5 on same Tariff £249 for the 16Gig and £299 for the 32Gig. Not Having a pop at the helpful poster I'm quoting, but it is a bit of a myth that Android phones are cheap and iPhones are expensive. It's just simply not the case. High end Android phones are priced roughly the same but with substantially cheaper materials and R&D. Although, a trade off is you do get a bigger screen and you get the obligatory 'throw everything into the phone even if it's not useful. Mind you having said that there are a few useless pieces of junk on the iPone 'Passbook' for example.
If you're going to use it for music, I personally think iPhone, especially if you have a Mac and want to transfer music. Android is utter pants for transferring music off a Mac onto the device, no idea what the experience is like on Windows. Otherwise I think the general user experience on the new Android devices has caught up a lot. Just be cautious you don't get a device that has to wait six months between OS releases and you being able to get the update, that's my main bug bear with Android these days.
If you use Quidco, you'll get £50 cashback for getting any of the above phones, excluding the iPhone