i havent gotten the ps3 yet, not because it's not a powerful gaming system that will suit my needs, but rather because of the lack of games for it
and I wont get it UNTIL those games are present, I'm not buying the system based off one gold mind (mgs)
the 360 avoids this problem I find, and generally has a better online service, but both fall short on the fact their backwards compatability is horrendous, and almost done as an after thought
the wii however allows you to play proper gamecube games, no patches needed (yay for mega man x collection) and moreover has a handful of solid titles, no more than sony right now, but the novelty factor and backwards comp. gives it a definite bonus, so as of right now, seeing as you arent considering the 360 (which I would suggest) i'd go for the wii, largley because you'll get your moneys worth immediatley