Warmaster Horus
Explorer
I'd like to see a low-magic, mythical setting (Greek, Norse, Celtic, Roman, etc).
I would consider looking at SpellJammer sans camp. Something like Jim Butcher's new Cinder Spires series would be really intriguing. I could actually see my group using that.
As it is, the existing SpellJammer setting is incomprehensible, to me, as far as the lure.
Did anyone mention Le Guin's Earthsea? It has no RPG that I've heard of, and I'd love to have it as a campaign setting.
I never understood all the Black Company love. Sure, they're good books, but for a really inventive world by Glen Cook I'll take Garrett and Tun-Faire any day. So Garret gets my vote.
I like the Black Company books, but there isn't much in the way of game-like progression in them, pretty much you are a superwizard or your not (also why I don't think a Dread Empire adaptation would work). Tun-Faire would rock, though, and the Darkwar books could make a nice scifi/fantasy crossover world--magic is more like a shaman thing, not so much spells, but spirits you have coerced to your will.