My first RPG was D&D back in the '70s.
Keep on the Borderlands, cheap plastic dice with hand-packed crayon in the numbers, THAC0, Pet/Poly, Rod/Staff/Wand, etc.
Since then I've played and DM'ed (in no particular order) Gamma World, AD&D, 3E, 3.5, Pathfinder, Roll Master, Champions, Fantasy Hero, Warhammer Fantasy, Fantasy Craft, Spy Craft, GURPS, Ritfs, Vamipre: TM, Star Wars D6 & d20, Pelicar, and probably 10 more that I can't think of right now...
I've also played just about every MMORPG: Ultima Online, Everquest, Dark Age of Camelot, Asheron's Call, Star Wars Galaxies, World of Warcraft, Guild Wars, and many many more.
I tend more toward fantasy, especially classic Tolkein or Howard style high fantasy or sword and sorcery. Lower magic and medieval tech as opposed to super-hero magic or gunslinger stuff.
I do like the occasional sci-fi or super hero genre game from time to time as well. Just not in my fantasy.
I've currently stopped DMing Pathfinder and its "Christmas Tree" magic and am now running Fantasy Craft instead.