I'm limiting the timeframe to 1993 and earlier:
sega or nintendo would have to be my faves. I think I'd lean towards nintendo. even the so-called "lesser" nintendo games (balloon fight!) just plain kick-ass.
Konami is a strong third (their pre-1994 era rules on NES, famicom, MSX, PCE, Genesis, SNES)...
of course i love hudson (4th on my list?), data east, taito, snk, etc. etc. etc.
but sega and nintendo just have too many awesome games (both at arcade and on console). yes, Hogan's Alley and Donkey Kong ruled in the arcade!
If I had to go with my favorite underdog: hmmmmm, Data East would get my love (Karnov! Bad Dudes! ).