If you ignore WotC as being in its own league, a handful of companies are now the “top tier” of RPG production. I’d include Mophidius there, with Paizo and Evil Hat, maybe Chaosium. Their products have extremely high production values and large (by TTRPG standards) followings.
The are mostly known for 2d20 games (Star Trek Adventures, Dune), Dragonbane, Forbidden Lands, Mutant: Year Zero, and now publish some more classic titles (Twilight: 2000, Kult).