The iPhone is available on o2, they offered me one last year, but like I said, I'd hate to have a touch screen with no real buttons, I like to text and walk without headbutting lamp posts Also I don't like the idea of such a closed platform, that's why I generally have symbian based phones.
I recently got the O2 Serra, otherwise known as the HTC Touch Pro. Its a pretty nice little phone. Touch screen if you want it but also has a full qwerty keyboard on it. Very customizable and proving so far to be a well rounded phone. I have it on the £35 a month contract which gets ma 600 minutes, 500 texts and unlimited web/data. I could have had the 600 minutes, unlimited texts and added a data plan ontop but you can take reduced texts and have the unlimited data at no extra cost.
Yeah the O2 serra is what I'm going for today. Their system was down yesterday, so I couldn't do it then