Infinity Ward, Activision, EA, and Treyarch
/thread
I hope that's sarcasm...
Bethesda is number one, but that's quite obvious by where we are. It's hard to pick a 2nd place, as a lot of companies are pretty decent. I'd say Valve, then probably Creative Assembly, Taleworlds, DICE, and then GSC game world.
EDIT: Can't believe I forgot Westwood, they'd be 2nd if they still existed... And Pre Blizzard-Activision Blizzard would score quite high on that list, but I can't bear to mention them and still feel complete inside. I hate you Kotick, you ruin everything nice about video games.
Rare, Pandemic, and 3DO were all great in their heyday. Black Isle, Headfirst productions, and Gearbox studios deserve honorable mentions.
SoE might be in line for redemption if they manage to not kill Planetside 2.