The latter is perhaps the most interesting game, although personally I don't think it's the best. In future vs. fantasy Quake you can take on numerous different characters each with different abilities. The game play is still a bit jerky, but the new 56k modems or a faster computer could solve that problem. Apart from Duke Nukem, not a single game has truly developed unique weapons. Other games all follow the Doom model which consists of a melee attack, a gun, shotgun, chain gun, rocket launcher, and some crazy weapon.
Quake follows that exact model, with a few twists.
I suppose they figured it was too unrealistic to send a one man army out to save the world with only a 9mm. Obviously if there's a shotgun there's going to be a double barreled shotgun, which releases twice the punch and takes twice the time to reload. In the super unrealistic category there is the Thunderbolt, a weapon that discharges lighting, is extremely powerful, but eats it's ammunition like popcorn. By the way if you do not like your body well done don't use this weapon under water. Quake's enemies are nothing out of the ordinary.