I think I prefer MOS since I must have watched it about 15 times!
Yet, I'll vote TDKR because I think it closes the trilogy in an awesome, unexpected way, and, all over, characterization is superior. I love MOS because I've always been a Superman fan, but I think MOS was too short, too much action packed and forgot character development somewhere along the way. It's more a "what could have been" than "what is"...
EDIT: got to admit I haven't yet watched ASM2, but if it's along the lines of the first one, it's utter crap!