It really depends on type of game you're playing. With racing and fighting games then Wii is the obvious choice but for puzzle games and 2D platforming, DS works better.
And FPS works great for both (Why haven't developers made more FPS's for the DS )
isn't this more a poll of wii vs. ds? because a touch screen would not work whatsoever on console games like the wii. you'd have to get up to do anything. motion sensing would work on the ds, though. since you couldn't use both functions interchangeably, you can't exactly compare them