I haven't actually played one, but I've had my eye on one for quite a while, now. So I've had a little bit of a wishlist built up in case I do make the plunge (but they're getting pricier and pricier, and I WON'T pay over $100 for one of these, not worth it).
What I've heard (or seen) is good and I'd want:
-Alone in the Dark 1 & 2
-D
-Dragon Lore
-Gex
-Need For Speed
-Night Trap (if you're intro trashy horror films like me)
-Road Rash
-Samurai Shodown
-Super Street Fighter II Turbo
-Wing Commander III
-Wolfenstein 3-D
All the 3DO fanboys rave about Star Control II, too. But it just doesn't look like my type of game. I've never been into strategy games much