Well I have all 3!!!!
So I can speak from experience.
360 is a f'n BEAST!!!! Every time I turned around I was like "Damn they really nailed that feature better than I could have dreamed!" HUGE Library FULL of A+++ games, online (while its 50$/year) smokes-SMOKES PS3 and WII put together!!!! With the upcoming ELITE version they addressed EVERY sortcoming of the original system (color,hdd size, hdmi).
PS3 is TRASH!!! Every time I turned around I was like "Damn they fcuked up that feature worse that I could have imagined!" There are NO games, they will come.... eventually, but the hardware is so awful it just isnt worth it. No matter when the GOOD games come out, the PS3 hardware is so awful......
Wii is cool, but its just a supersized gamecube, not a next gen system. While the controllers are cool, the novelty wore off, I spend most of my time playing retro games that play better on their original console. And the wii just doesnt stack up to the nextgen games of either ps3 or 360. Forget online play as is is not more than a ghost, and nintendo is notorious that if it aint available at launch it prolly will be vapor ware for the life of the console.