PS3 > Wii > Xbox 360.
If you're going to sell your Wii, get a PS3. And if you already have a PS3, then don't sell your Wii. I don't really suggest Xbox, because it's stupid. Microsoft is just stealing ideas... Then again, so is PS3.
Anyways, if you do this get a PS3, and if you have a PS3 I would say don't do it at all, just sell the games you don't care for.