played xbox a little, hated the larger controller and not too many games that are exclusive that i liked.
own a gamecube and love it. like others i didnt like the shipped controller so i bought a wavebird controller (official nintendo wireless controller) and love that. many of the games are kinda kiddy, but they make up for that in fun factor.
i would go with gamecube cause of price, games, official wireless controler, same room multiplayer.
woudl go for xbox if i cared more about gfx (doesnt make a game though), online play, halo.