First of all, the Jaguar is not the best console. You might be better off getting a 3DO, N64, or PSX. However, if you do have this, there are some very good games for it, although the library certainly isn't as memorable as some other fifth-generation consoles.
The List
Box
Title
Genre
Description
Tempest 2000
Fixed Shooter
Probably the best game on the console. First of all, this soundtrack is pure awesome. In fact, the soundtrack was even released as a CD.
You play as a ship, fixed on the edge of a colorful "web" and you shoot incoming shit and get powerups. Very addictive.
Alien vs. Predator
FPS
Play as an Alien rescuing the Alien queen, a predator trying to kill the Alien queen, or as a marine trying to get the fuck out of there. Marine campaign is by far the best, although all three of the campaigns are good.