They do a great job at telling you the story and lore without putting it right in front of you. Coupled with enjoyable gameplay, and a decent plot line.
They also manage Steam, which almost takes control of all of the PC video distribution. Almost, I had to get Battlefield 3 on Origin
The ones that make good games. So, I'm not going to buy a game if I find out that a certain company made it. But certain companies I see over and over; Nintendo, Ubisoft, sometimes EA, that's all I can think of right now.
Bethesda all the way, with Bungie as a close second. Bethesda did an amazing job on fallout and elder scrolls. The recent Skyrim game shows how much effort and detail they work to put in it. Very dedicated and hardworking. I haven't played any of their games that weren't good...