How about....none of them!
Nintendo Wii is just gonna be a bunch of lame ass puzzle games that require you to shake the controler in some weird way. I'm all for innovation in the video gaming market, but Nintendo goes about it the wrong way. Sometimes all you want to do is pwn some n00bs, not play with plankton, giga pets, balled monkeys, or Pikmans.
As far as I can tell, X-BOX 360 is just a glorified X-BOX. Whats the point of shelling out $450 for a new console and hundreds more for a decent gaming library, which, as Simsy pointed out, are all being released on current systems.
And as for the PS3...I dont have $500 to shell out for the gimpy version of the console, let $600 for the good one.
If I get any of these systems, (like any console) its gonna be after at least a two year wait, once the price has gone down considerably and a good amount of decent games have been released.