I'd say that personally, Wii easily has a better lineup than the GameCube. As a lover of all things platfomers, the Wii is truly a jumper junkie's best friend. And with Super Mario Galaxy 2 and Sonic the Hedgehog 4 coming out this year... the cycle continues.
Though from my point of view I still think that GameCube surpasses Wii when it comes to RPGs and FPSs (the two genres that really don't grab me). But other than that... I see the Wii as one amazing console with an amazing lineup of games.