The best cards for gaming:
Choices for a low (386 or lower PC)
FM Synthesis:
Sound Blaster Pro 1.0 - 8-bit digitzed sound at 44.1kHz sounds better for games that support it; fully downard compatible, except for Game Blaster, has mixer and better sound output quality. Sound Blaster Pro 2.0 do not support stereo FM of the Pro 1.0, and Sound Blaster 16s or better also do not support stereo digitzed sounds, filtering or stereo mixing of the Pros.
Roland:
MPU-401 + MIF-IPC + CM-32L - Some games use its 33 extra sound effects which the MT-32 doesn't have. Can substitute perfectly with an LAPC-I if you have no interest in an external module.
Other Interesting Options:
Innovation SSI-2001, Covox Sound Master, Covox Speech Thing or Disney Sound Source, Creative Game Blaster, IBM Music Feature Card.
High end PCs (486 & Pentium)
Sound Blaster
Sound Blaster 16 CT-1740 or CT-1750 - True OPL3, 8-bit and 16-bit at 44.1kHz, dynamic filtering, mixer with separate bass & treble parameters, ASP chip, DSP of 4.05, waveblaster connector. I don;t like the CT-1770 because it uses an extra IRQ for the SCSI-2 interface, and the later 16s lose the OPL3 chip and sometimes more.
General Midi
Roland SCM-15AT - A combination of the MPU-401AT and SCB-55. Same midi interface as the SCC-1 but more sounds, more voices & better DAC.
Other: Gravis Ultrasound (Ace is most convenient); Ensoniq Soundscape (Elite w/ daughterboard is best); Yamaha DB50XG or SW60XG; Adlib Gold 1000 (w/reverb module for Dune).