I personally haven't owned a Nintendo since the NES (my younger brother had an N64, one of their better offerings) and so far I don't see any reason to break that streak. The only two titles that interest me so far are Mass Effect 3 and Arkham City, both of which I already own and I see no need to repurchase them for a new system. Perhaps later on, they'll have more games that warrant buying a whole new game system, but if it's just better looking wii games, than I'm not interested.
When I play games, I want to use a controller, preferably a 360 controller.