I played an XB and GCN at a Wal-Mart, so I was able to compare them directly.
The XB controller isn't horrible, but it does suck. The GCN controller is awkward, but it just takes a second or two to get used to. The fact that you press L with your pointer finger and R with your middle finger...
I know many will disagree with me, but Zelda is one of the reasons I'm initially going with a GameCube. MS has good games, but so did the Sega Saturn, and I never got one of them.
I will be content with my PS2 through next spring, but I want a GCN, so I will be getting it as soon as possible.
Just looking at launch games, I like Nintendo's lineup more. I could care less about Halo because I have many other good FPS games to play, and on the PS2, they could end up going online soon. DoA3 is close to DoA2:H in terms of gameplay, and I have DoA2:H. Also, looking at the games coming...