Paizo. And I don't play Pathfinder either (though I like their adventures, and I've stolen some of the mechanical bits that I like...

) In my opinion, they are the only one of the top RPG companies currently doing
everything right. Good quality products, an extensive but not overly saturated product line, and most importantly: phenomenal public/customer relations and involvement. Their relationship with their customers is the factor that's pushing them to the top of the industry. Want to know how to take a company to the top of the RPG mountain and keep it there, then pay attention to how Paizo interacts with their fans and customers. They are now the industry standard for this.
But, I have to put a vote in for
Open Design also. Not a huge RPG company. Not a very large product line. Not even their own system. But the stuff they make (for other companies systems) is of the absolute highest quality. I agree with some of the above posters, Kobold Quarterly is the spiritual successor to the print Dragon and Dungeon magazines. And some of their stuff even go beyond just professional gaming publications and enter the realm of classic epic fiction (i.e.:
The Red Eye of Azathoth...I can't wait for this to come out...it's getting so close

). Probably the best
quality in the industry right now.
Also, I have to put a vote in for
Fat Dragon Games. They do some actual RPG books (for other companies systems), but their printable terrain products are the absoulute best anywhere! There might be some printable terrain products from other companies that are
individually better, but Fat Dragon Games line is the most comprehensive and all-inclusive line in existence, with industry standard setting quality and unmatched practical usability.
Lastly, I'm going to drop in an off-beat vote for
Ki Ryn Studios (Ryan Wolf). The Future Armada line is the absolute best line of products for sci-fi/future spaceships,
EVAR! The included art of the vehicles in action, is what puts Future Armada products above other spaceship products. Not just a grid map of the vehicle and the vehicles stats, but professional quality, realistic looking computer generated pictures of the vehicles in action in assorted settings, environments, and from various angles. The pictures are what make them come alive. Show a group of players a grid map of their ship and a stat sheet, and they'll respond well enough. But show them a cool-ass picture of their ship in action, and you've instantly got them hooked. Nobody else in this niche provides this with their products. Ryan Wolf's attention to detail on this line (even though it's a rather small niche product line) has set a new standard for the quality of these types of products. Quality wise, they're light years beyond any other similar products on the market.
Lastly-lastly, I have to add an honorable mention to
EN Publishing also. I'm impressed with the new license for Santiago, licensing War of the Burning Sky into an MMO, and developing another new epic AP...along with all of the cool little products they've made over the years. I've bought and integrated quite a bit of the little mechanical goodness they've published. With the increased presence of ENWorld, Morrus is really starting to make a name for himself and ENWorld/EN Publishing. And we can all say I remember him when...
