I'd have to say the PS3 and XBOX are best for shooting games (I regret getting a Wii now. Thought it would be good for shooting games but is only good for rail-shooters or w/e they're called). The only problem with those three systems is that only certain games are on a certain system even though they could probably be compatible (ex: Left 4 Dead is only on Xbox. Fallout 3 isn't on the Wii. Not too sure if Resident Evil 5 can work with the Wii but I wish they would make a Wii version).
ps3 is the best if you are an older gamer or a gamer that really cares if not its not worth the money. Xbox is really only good if you got the 60 bucks or whatever to spend on live and a wii is fun sometimes