I have to agree with Grey Fox. I never even finished Star Fox Adventures, I got so bored of the large, usually baren, levels with enemies that comprised no more skill than just jamming the button with no fear of being hit. The graphics were good... but it's a game I am sorry I bought. Anyway, my personal recommendation list:
Super Smash Bros. Melee (GET THIS! My sole reason for owning a Cube, got it the day it released, and still play it)
Time Splitters 2 (if you don't own on another system)
Metroid Prime
Soul Caliber II (if you don't own on another system)
Roque Leader (or might just hold out for the third)
Skies of Arcadia Legends (if you don't own on another system)
Legend of Zelda: Wind Waker
There are tons of great games for the cube, but out of the 30 I own (yeah, even number) these are the cream of the crop IMO.