You can all argue over who the 'kings' may be, but indie developers are the unsung heroes.
Minmax and Chillingo are two of the best unsung developers:
Chillingo has made Feed Me Oil, Cut The Rope and Angry Birds which are 3 of the best handheld games ever.
Minmax, a two person company, made Space Pirates and Zombies...play the game and tell me you aren't completely floored by that fact.
Of the big ones I have to say Rockstar as the definitive king and runner-ups being Bioware(to the void with all of you haters), Ubisoft, Nintendo, Bungie, Lucasarts and Bethesda.
There are only two companies I can currently think of that have not made a bad game:
Blizzard
Ensemble Studios(rest in piece)