I own the Wii (selling it now) - The Wii is an awesome little console. Don't get me wrong though, while it's still a great console, it's kind of a let down as well. The console its self is great, but it's the selection of games.
Allot of the games that have come out for the wii are just classic remakes of PS2 titles and arcade titles, and of course... the whole mario franchise. I have red steel and Zelda for it, and they are really really good. I'm just disappointed with the selection of games that aren't MARIO, I personally would like to see more mature games like zelda and red steel. Manhunt 2 was kicked to the curb because it was too violent. It's coming back out in december, but still.
Nintendo has just really bugged me because I have this console that has so many capabilities and no one is getting a chance to see or show what it's made of, they take all of the good ideas and games, and ban them and saturate the marked with stale remakes from 6 - 8 years ago. Really.. it's a bummer. The lack of great titles isn't the reason I'm selling, I'm selling it because I haven't played it much, I love it, and I don't want to sell it. But, i'm not using it, so it should to some one that will use it.
I'd prefer an xbox360 over the ps3, it's much better. Microsoft has had trouble with heat issued, but they are being addressed (or are). Not every console will over heat. They just extended the warranty to 3 years, so if it fails to perform correctly you'll definitely have time to get it fixed. The games are unreal on the 360, really.. I don't think you'll be too dissapointed with the 360, it has great games and a huge library of original games.. IT's fab.
The ps3 has lots of potential, but it's that price that makes it a bad choice, you're going to go broke before you can even play it.