I have all 3 and at the moment the 360 is the better choice, providing you like first/third person shooters. The Wii feels like a bit of a gimmick to me, as the controller limits a lot of genres. Its game library isn't anything to brag about either, with only a handful of enjoyable games which can mostly be enjoyed on the Gamecube minus the horribly unoptimized controller (TP anyone?). That being said it's still an awesome party device as it has the potential to make even the simplest games incredibly fun.
The PS3 has a lot of potential beneath it's black, shiny exterior unfortunately, like the Wii, it is hindered by its current game library and unfortunately spends most of its time either playing BR movies, or folding continuously for days on end. However Resistance is a pretty good game and its multiplayer is about the same in terms of goodness. By the time MGS4 comes out I'm sure it'll be a solid choice. Ehehe...
Anyway, at the moment the only console that can be judged is the 360, the other consoles are still on their first generation games, making it kind of pointless to compare them now. But if I had to choose between all 3 I would personally get the 360 due to the surplus of AAA titles and it's awesome online service, after that would be the Wii then PS3.