3DS right now since it's starting to grow really strong. PS3 is... ok, but I don't care for any of the exclusives or the anime games, so my opinion on it is biased.
idk its on your personal preference whether you like a portable or not. It also depends on what type of games you like to play if you like better graffics i would recommend ps3. If you like pokemon I would recommend 3ds as x and y will come out soon