I'm gonna say the wii too, not because of the power of the hardware (such things don't bother me, I'd happily play something that looked like Mario64/OoT64 on the wii)
But i can look at my other nintendo consoles, and see the rich library of games, even from third party developers and be excited to play them. Every nintendo console had classics and instant classics and game you knew were good from the off and games that would be good so much further down the line.
With the Wii i don't feel that at all, i have a rich library of games on the wii and really none of them compare to the brilliant titles i've played on the n64, GC and the Snes. Out of the 30 games i have for the wii i can say that only 5 have really been worth playing and even the i've felt those games to be lacking in what they could have done (SS for example).
I',m not against motion controls either but they are fickle and their inclusion has ruined some Wii games for me. I could pick quite a few games for the wii that i would have preferred to play with buttons and in my opinion i think i would have enjoyed them so much more.
The Wii, to me, is only okay, the games are only okay, they way that we are forced to play them is only okay. Very rarely was a game for the wii stellar and i don't think any game released was much of a revolution or deserved the praise that they got, and that is including the Mario Galaxy games.