What??! No Gamecubers? Come out of the woodwork. I agree w/ the sentiment that the type of games really makes the decision. For me, I like the fun, quirky, unique games like the mario franchise, Zelda, Resident Evil, Metroid, Eternal Darkness, Pikmin, etc. I have a Gameboy Advance that also connects to it. I use component video to my plasma and the picture is great, there are a number of 480p widescreen games that look awesome. The only complaint I'd have is that audio is only 2 channel Dolby, no digital.
The other platforms are good and so are the games. Halo 2... It also helps to have friends w/ whom you can swap games.
