The DC version of Rez is the worst one anyway. And the Sonic Adventure games were creaky and lame (classic 6/10s) when they came out, I doubt they are worth playing today.
The DC is over a generation old, so you should be careful and not just get games acclaimed when they came out. Advances in 3D and game design have made a lot of games of that era obsolete. So 3D titles like MDK2, Rayman 2 (which was actually ported from the N64), Jet Grind Radio, and Fur Fighters I would be careful with. Plus, that controller is a dog.
If you like shmups there are LOTS on the platform, including Giga Wing 2, Mars Matrix, Zero Gunner 2, Under Defeat, and Border Down - five excellent games not on any other platform. There's also Bangai-O, and I think a DS sequel is coming soon. Actually arcadey throwbacks (this includes fighters) is where the system excels and is its legacy.
Possibly my favorite game on the system is Virtual On, but without the Twin Sticks don't bother. They can get very expensive. Typing of the Dead is a great game too, but you'd have to buy the keyboard, and there's a PC port anyway. The Shenmue series is cool, but you can get Shenmue 2 on Xbox for like $3.99 from any GameStop (I actually recommend doing this).