Turrican 2. Music rox, and greatly "synchronized" with the intro sequence
Flashback. excellent soundtrack for an excellent game
Z-out. Quite old (89 or 90) but excellent. I never played Project-X so I don't know if it is the best shoot'm'up soundtrack...
Shadow of the beast. Cool
Xenon 2: (perhaps) not the worse, but how can you call this a soundtrack since there is only *one* music for all levels...how boooring... :-D