Bungie, Valve, and Double Fine.
All good to their respective communities. Well, Valve could release games a little more often, but when they do, it's often worth the wait.
Double Fine always has that Double Fine feel to their games, and it's great. Even when I played Brutal Legend, I didn't really like the gameplay, but the feel of the characters was still great.
And Bungie. I don't care, I love 'em. They made Halo, but passed it on to another company so they could make other games. None of which we've seen, but I have high hopes.
EDIT: And Nintendo, since that's what started my love of games, back with the Gameboy Color, Pokemon Gold, and The Legend of Zelda: Oracle of Seasons.