Blizzard- Because of all the RTSs they did, not because of WoW.
Bioware- They're one of the best, if not the best Western RPG developers around.
Valve- Anything made by them is gold, ANYTHING!
Infinity Ward- Say what you will about them, but without them Call of Duty wouldn't have existed.
Team Silent- Yeah, they're not still around, but all the games they made were awesome (sadly, they only made four games)
Ubisoft- Ubisoft are pretty good, they've made some pretty awesome games.
2K Games- They've made two games which are in my favorite games of all time list.
Capcom- Yes, they are both developer and publisher, but they've made the Ace Attorney series and also, RE4.