I would really think Xbox - but only if the xbox online service will be available in your area. If not, then the xbox's games (or atleast the ones that are coming out now) are worthless, so don't get xbox if you won't be able to play online; there aren't enough strong games that are NOT XBL Enabled that you can serriously enjoy IMO!!!! NO CONSOLE WARS!!!
I think, if you HAD to get gamecube, then do so. It would be a better desicion than xbox if you cannot get the online multiplayer, and there ARE some good games (resident evil, supersmash bros melee (just tried that game - it rocks

), rouge squadron, etc.!).