Personally, I liked the old one better. It was easier to make bells, and the controller vibrated when you were fishing so that made it a lot easier. Fossils weren't as rare, and there were NES games that some people never got to experience. The items were better, and the characters too. They gave you jobs. You had your own house. Try sharing it with a mom that likes the regal theme...
If I had the choice between one or the other, I'd choose the Gamecube version.
~Tikal