I had a Samsuck Craptivate on AT&T, since it was the only decent phone on AT&T at the time (spec wise, turned out to be a POS). I ended up switching to iPhone because I'm on the AT&T family plan, and they are the dominant carrier around here, and I'm very happy with it. There are some things I miss, but it also does some things a lot better. The Craptivate was poorly built, they never released official software updates, and it's RF performance was bad.
EDIT: I didn't consider an iOS device before iOS 5. Apple gradually fixed everything that was wrong with the iPhone, piece by piece, starting with copy and paste, MMS, the battery life, multitasking, and finally adding a notification system. Without all those pieces, I would have gotten Atrix 2, just for having Moto hardware.