Bethesda, I adore Bethesda for making the best game ever created.

I also love Ensemble, Splash Damage and Raven.

Nintendo (Tons of classic games!)
Blizzard (Addictive and always top-notch games)
Squaresoft (still like Square-Enix but not as much as Squaresoft)

Square Enix
Any Sony first party studio
Retro Studios

Nintendo, Valve, Firaxis, Relic and Maxis from the good SimCity era (pre SC4)

From this gen

Atlus, Bioware, Bethesda, Kojima, Naugty Dog and Team ICO

I wasnt into gaming last gen as much as i am this gen.

I see so many good devs in this thread :P

I'm gonna go with~

Sony Computer Entertainment. Back in the PS2 era, I didn't really focus on who made what, but now that I think of it, they really do make amazing games. Some of my favorite franchises over the years, and ESP so with this PS3. They're network and first party games are just stellar. And most (if not all) of the titles are absolutely impressive on a technical level. I think they're artistic, technically impressive, and just overall great games. They get the box of kudo's.

Square-enix (although they're slowly fading as of lately). PS2 gen and before, these guys were just insane. I have so much respect for squaresoft, from Chrono Trigger, Final Fantasy 6-12, Secret of Mana, xenogears gah, everything they touched turned to gold ^_^ They always pushed tech, and they're games were just masterpieces. Some of they're recent titles really left that wtf feeling in my mouth, but at they're core, they're just brilliant.

Team Kojima. These guy's, defined pointless attention to detail for me in games. I played metal gear solid a bit late, so was never really able to appreciate it's technical prowess, but when MGS2 was released, holy balls... that's all I can say. These guys are truly masters of they're craft, and some of the best developers on a technical level that the world's ever seen. Rock solid frame rates, cutting edge tech on graphical achievement, nary a graphics hitch to be found. I've used the expression so many times, and it really coins it for these guys. They're games BEG you to find flaws. And I really dig that. Any of you remember shooting the ketchup bottles in MGS2 and watching them break at different places? Just insane!

Nintendo. They're REALLY lost base with me with they're recent titles. But from a technical standpoint, I really can't argue with the quality they "can" put out for they're flagships. A technically amazing company and some of the best dev's around.

Epic Studio's. I think they make a great engine :) And it's very capable. These guys know they're shit.

Bioware. While I don't consider them the best games on a technical level, they're almost always good. And they know the character build soooo well

Rockstar - Grand Theft Auto, will likely buy LA Noire if it ever comes out.

Polyphony - Gran Turismo is freakin awesome, too bad they don't make other series AS WELL as GT.

Naughty Dog - Ever since back in the Crash Bandicoot days, and now Uncharted.

Infinity Ward - The Good Call of Duty games

Tose.

CRITERION!!! These guys are amazing!!! They're games been out for a while, and they're still supporting it ^_^ They are brilliant developers and put out a very polished product and they're very adamant about PS3 development :D Which puts them in a league of they're own as far as finding tech is concerned. I love j00 criterion!

Naughty Dog
Kojima productions
Insomniac
Sony Santa Monica

and... CLOVER for make a piece of art with OKAMI