Childish banter aside, I'd (obviously) have to go with Nintendo. Now, as I sure most of you have discerneed by now, I don't agree with some of their recent business decisions and software quality, but they do have three things going for them that neither Sony, Microsoft, or anyone else can top:
1) They've been around for over a century; the whole "casual" obsession of theirs lately irritates me as much as the next guy, but I'd like to think that they know what they're doing.
2) Perhaps aside from being the majority stockholder of the Seattle Seahawks (it's true!), they're about games and that's it. Sony? Electronics, TVs, movies... Microsoft? As far as they're concerned, the 360's just Windows with shoulder buttons and rumble. To these companies, videogames are just an extension of their line(s) of techie products. With Nintendo, though, they can focus on games and consoles alone.
3) They're not afraid to innovate! The E-Reader, GCN/GBA connectivity, the Virtual Boy; the list of Nintendo's questionable creations go on. But they also pioneered the D-pad, A/B/Start/Select, rumble/shoulder buttons (correct me if I'm wrong here), first-party wireless controllers, and, of course, the DS/Wii. Once again, I'm just as displeased with how a lot of said DS/Wii game have turned out, but you've still got to break a few eggs to make an omlette, and these shaky beginnings could be the groundwork for something great. Since when have Sony and Microsoft done anything original? They just follow the leader, clean up the graphics, and amp up the cost.