Perhaps OP can share what kind of gaming experience he's looking for, because this really boils down to what kind of games do you enjoy more.
Has for the hardware itself. Both are awesome in their own right.
I had access to a 3DS and played for couple hours New Super Mario Bros 2 and the controls are perfect. Also experimented other titles and for instance, in the Resident Evil Demo, I didn´t like how the circle pad works for that kind of game.
I´m playing Wipeout 2048 on my PS Vita and the analog sticks work very smoothly. Also in my experience with Silent Hill: Book of Memories, you can control the movement speed of your character with excellent accuracy.
In my first post I recommended PS Vita, because of the games (personal taste) the machine itself and if you are a PS3 user and happens to have PlayStation Plus you know it´s value (Instante Game Collection and other services). But has I said it depends on what kind of gaming experience are you looking for.
