I think if you want the same old gameplay, with better/great graphics... go for the PS3/X360. If you want a completly new gameplay experience... go for Wii.
I personally grew tired of the same old gameplay some time ago, during the GC days. I think the Wii is like going from SNES to N64, rather than N64 to GC. So yea, I prefer the Wii ^_^.
BTW, I think the graphical standard of Nintendo Wii games will be (hopefully quite noticeably) greater than that of current/previous (PS2/GC/XBox) systems. But seriously, look what they have managed in Legend of Zelda: Twilight Princess, and that's just using GC hardware ^_^. So yea, I think I will be more than happy with the graphical power of the Wii.