I've always preferred playing the casual type shit on portables. If I wanted to play an FPS or RPG game that isn't 2D then I'd definitely want to do that on a home console like a PS3 or Xbox 360.
Who gives a fuck about the hardware and what it can do, the only important thing on a portable console are the games. Just take a look at the existing and upcoming games on each and see what you'd rather be playing.