Right this is quite trivial I know.
My contract is up shortly. I have iPhone 4 ATM. Am debating with the easy but more expensive option of iPhone 5 though I'm not convinced they have made enough changes from 4s to warrant the price. I say easy as I have a rather difficult 4week old ATM and it would be a case of swap sim and away we go)
Or
The Samsung galaxy s3 (I think that's the current one). This would be the cheaper opti