The GameCube gets my vote. It was by far the most interesting console in the previous generation, with games such as Super Smash Bros. Melee, Metroid Prime 1+2, numerous Mario/Zelda games as well as a solid library of third-party games. Right now, for me personally, the GameCube has a far, far better library of games than the Wii does right now, and even all the notable "true Nintendo" Wii games such as Metroid Prime 3, Super Smash Bros. Brawl, Pokemon Battle Revolution and LoZ:Twilight Princess have failed to stand above their 'Cube counterparts - I personally consider Metroid Prime 3 to be, albeit still very good, the weakest in that trilogy (Hunters doesn't count,) I consider Brawl to be noticeably worse than Melee in almost all areas thanks to Sakurai being a complete moron, PBR fails to match even Colosseum and XD, let alone the Stadium games on the N64, and overall PBR feels like a rushjob in all areas, and my brother has stated that Twilight Princess is much worse than the Wind Waker and Four Swords Adventures in his view.
GameCube all the way for me - the DS and Xbox 360, while close, haven't been able to take the top spot from the 'Cube's epic-ness, and unless Metroid: Other M turns out to be better than both Super Metroid and Metroid Fusion combined, the Wii will not be beating the GameCube by a long shot.
On a final note, I have to agree with Stel about the PC - my PC was the first "games console" I ever had - whilst everyone at my primary school had their Playstations, their Tekkens and Final Fantasies, I was mowing down hordes of Nazis, mutants, zombies and demons on Doom and Wolfenstein 3D. Since I was only 8 years old when I first played those games...it'd probably explain a few things about how I ended up being the way I am now.