Gamecube, I tried Wiimote and Nunchuck, it's a nice backup I guess.
and the Wiimote on it's side doesn't look as intimidating because it only has like 3 useable buttons on the front, so it would be good to give to parents or noobs
Wiimote on its side is meh. Wiimote + Nunchuk combo is OK, it's fun to use the motion sensor for smashes. haven't tried classic controller, but heard it's just as good as the GCN pad.