valve and blizzard are the two best video game developers around nowadays
They consistently make only quality products, and stick to what they due best (until they come up with amazing ideas like portal and wow). Most people believe blizzard scrapped Starcraft: Ghost because it wouldn't live up to the standard that blizzard games set for themselves. You gotta respect that
As far as best video game developers of all time? I dont know.
Capcom is pretty good, being extremely successful in several different kinds of genres (for example street fighter series, resident evil, megaman). Might even be worthy of being grouped together with Valve and Blizzard. Squaresoft was godly, but idk what to think of square enix now since I hardly play any of their new games due to lack of a next gen system. Nintendo had some amazing games, but Ive been too disappointed in them in the last few years to consider them a video game great anymore. Besides, even melee's gameplay was just a wonderful wonderful accident.
and of course
Id for making my FPS experiences possible by making Wolfenstein, and for starting my video game addiction with Doom (Commander Keen was awesome too!)