After fixing a 360 and a PS3 now, playing a Wii many times, and now owning a PS3, I think I've formed a more-informed opinion on the matter.
Nintendo's cutesy image just doesn't do it for me, aside from the fact that as far as technology goes, it fails (yes, I'm one of those guys that loves a game just for its aesthetic value. So sue me.) I know it has more "adult" games now, but I still leave a game feeling like I just played a kid's game.
The nunchuck/controller/whatever set up is "meh" to me at best. Nothing special.
No Bluray.
The 360's controllers drive me absolutely batflax. They are also unthinkably loud; I was completely surprised on the noise level. Our network server at work is about the same noise level. At least it quiets down after a while.
The 360's beginning price point only works for the white console, otherwise you need to get the "elite"... which costs as much as a PS3.
No Bluray.
The PS3 is expensive. Obnoxiously so. The games aren't any better. The controllers aren't cheap, either. I have two games, two controllers, and a PS3 slim, which cost $415 altogether. Insane.
Furthermore, homebrew/backups/HD storage isn't all that possible at the current time (if ever?)
But, the PS3 has Bluray, natively streams movies wirelessly from the PC, and has access to downloadable content. (Does the Xbox have these features, other than Bluray? I don't know, really.)
To address each systems' downfalls, from my own perspective:
Nintendo:
Answer to cutesy image: Xbox/PS3
Answer to technology fail: Xbox/PS3
Answer to controller issues: Xbox/PS3
Answer to age-appropriate game content: Xbox/PS3
Answer to lack of Bluray: PS3
Xbox:
Answer to controller problem: PS3
Answer to noise problem: Wii/PS3
Answer to console aesthetic: PS3
Answer to lack of Bluray: PS3
PS3:
Answer to expense: Wii/Xbox
Answer to lack of homebrew: Wii/Xbox