Pros and cons of each
PS3: Most powerful graphically, best hardware. Just too expensive for many to get
xbox: probably has more games that people like. and it was first to release. xbox live. nothing extremely bad, except perhaps the weaker performance compared to ps3
wii: very innovative. Not so traditional. also is the cheapest. Has the crappiest graphics. also, i personally don't like the way the controller works.
Each has their own style, but for serious gaming, wii is out of the race for me.
So i would choose xbox due to price and a better choice of games for me