Sonic Adventure 1: One of the best 3D platformers ever released. People bitch about Sonic not working in 3D, but I think SA nailed it.
Ecco the Dolphin (DC): It's hard and has some rough spots, but it is one of the most beautiful games ever created.
Luigi's Mansion: I just like it, but I can see why others don't.
EDIT- After going through the thread, here are some others: Tokyo Xtreme Racer, Rush 2049, Wave Race: BS, C&C: Tiberian Sun...