Xbox is technically better for offline purposes, but since the controller is absolute shit, PS3 is used for tournaments.
For online, there is no difference, it's the same.
The only difference is that you pay to play online with Xbox.
Controller preference=Playstation hands down.
But I don't use one, I use a stick, so idk.
MK10 isn't due until 2013 according to rumors............so just get mk9, it's an overall awesome experience.