So far I'm not impressed with the Wii. I played with one for a bit at a Gamestop. The only game that seemed to be available was ExciteTruck. It was an okay game, but the Wiimote doesn't make a satisfying controller for a racing game, even an arcady one like ExciteTruck. The complete lack of resistance to your movements is very awkward at first. You get used to it after a little while, but it still leaves you with an unsatisfying tactile experience.
Motion sensing game controllers is nothing new. I think looking at past examples rythm games, "light-gun" games, sword-fighting games and certain types of sports games will work well with the Wii controller, but I'm not convinced that other games will. To an extent, modern arcades survive on their wacky control schemes since home consoles easily match what arcade machines can do graphically and the arcades are certainly no strangers to motion sensors and similar technology. If anyone had a vested interest in pushing the boundaries of funny motion sensing controllers you would think it would be the arcade manufacturers, yet you don't see them venture out of those genres with motion sensing tech. Granted part of this may because not all genres work well in an arcade setting, but it still doesn't inspire confidence.
Perhaps I'll change my tune when I get to try some of the other games, but for now I have no interest in buying a Wii particularly with the $250 price tag. It's too much for warmed-over last-gen hardware even if it has a fancy new controller.
The 360 has my interest at the moment. Graphically speaking, Gears of War looks better than anything I've seen for the PS3 so far (though I've only seen screenshots of PS3 games so far) and while it's pretty standard fare as far as shooters go, the strong support for multiplayer coop is a nice feature. Dead Rising seems to be a great game from the little bit of time I've spent with it and there are at least a few other titles that seem pretty interesting so far. The fact that the door is at least somewhat open for homebrew is also a plus.