The only thing I've noticed between the samsungs and HTCs is that the HTC's seem to be better built. A bit more heavier and robust and not as plastic as the samsungs.
3 seems to be doing good deals in term of data but being on 3 is like having a rabbit phone. No one had one
I'm currently on a palm pre on webOS. Like the op system but gonna move to android in october. I think android is more flexible especially with google mail, calendar, contacts etc etc