No Microsoft for me.
Everything else: hell, yeah.
I slightly favor Nintendo over Sony, but not by much, knowing that there are annoyances with every bigger company. However the GC is a nice piece of hardware, too, aside from the default colour (I got a platinum one which looks great, yay!). Too bad it didn't get enough support. And I still use the PS2 for watching DVDs. I don't own a standalone player.
Must have titles on both systems. Games I own are about even between the two with the PS2 ones forming a small majority. Probably formed by games that sucked like Galerians: Ash.
Fortunately my disgust for MS didn't hurt me so far. I'd be only interested in... hmmmm.... some multiplatformers perhaps. And some DOA, if they got rid of the horrible music that infested DOA2. I'd also be willing to try Halo although I truly suck at FPS.
EDIT: I've got a strong feeling that Revolution will rock so if I had to support only one company, it'd be Nintendo.