As a huge Nintendo fanboy, I say it again: The XBox 360 is the only one that isn’t garbage. That isn’t to say that it’s a great system either.
Bear in mind, when I say “great games” below, I mean universally awesome games, not niche games. I love Elebits and Star Soldier R, but those games are unfun to 90% of gamers. Having a bunch of aweosme niche games IS a plus, but it doesn’t make it a great console. Like the Dreamcast and Saturn.
Wii: Has about 2-3 great exclusive games: Super Mario Galaxy, Metroid, and maybe Zelda, plus a bunch of old games. Brawl is a trash competitive game, especially when put next to Melee, and is only an alright party game, depends on who you hang out with. Piece of trash online service too on the Wii in general, but it’s free. Basically Wii is a console you play a bunch of Wii Sports, Zelda, and Mario on, and then it collects dust.
PS3’s only exclusive great games are Metal Gear Solid 4 and Resistance. All the none-exclusives have far better online with the 360.
360 meanwhile has a bunch of great games, exclusives as well, the best online service by far, a bunch of great niche games off of XBox Live Arcade in addition to strong system-sellers. Every genre from RPGs, shmups, shooters, puzzle, adventure, beat em up, flight, and platformer all have plenty of support on the console. Lots of content. It’s not really that great of a system, especially since I hate 360 system sellers like GoW, Halo, and GTA, most of my games are XBL Arcade, but has lots of good games niche and mainstream from all genres and the best online support. It has the system failure problem as well, basically making it the new PS2. At least they’ll replace your console for free.
Summary: PS3 and Wii have little content and shitty online. 360 has a bunch content and great online service, but you might have to wait a few weeks for it to be repaired. Really, the only reason to get a PS3 and Wii is for the next games of your favorite series like Metal Gear Solid, Gran Turismo, Zelda, Metroid, Super Smash Bros., Mario, etc.