Based purely on devs who made games that sucked me in, moved, inspired and entertained me the most and for the longest time I'm going to have to give it to Bethesda and Bioware.
Bethesda for both entries into the Elder scrolls series this generation, including associated expansion packs (yes yes I know; horse armor, calm down) and to a lesser extent Fall out 3 which was great in scope and atmosphere but try as I might, I couldn't get absorbed in the post apocalyptic dystopia.
Bioware for the Mass Effect series which I often worry i might love just a little bit too much and both dragon age games, which I managed to thoroughly enjoy despite some unfortunate flaws and design oversights.
Hounourable mentions go to:
Ubisoft montral, managing to have us murder countless englishmen, arabs, frenchmen, italians, turks and americans while still holding a valid message about racial balance and harmony and a strong moral imperative. Good job there.
Rocksteady, getting me even more interested in batman than christopher nolan did
Lionhead, Fable 2. Not so much Fable 3, though I enjoyed that as well.
Volition, proving you can out-silly yourself successfully
Relic, for some valiant attempts to bring the warhammer 40K Universe to life, even if they did come up with mixed results
Team Bondi, for struggling through the harsh strictures of an unforgiving buisiness model and recieving no reward at the end. Certainly not the only such story this generation, but it stands out in my mind as one of the most severe, especially since LA Noir was a real result in innovation, if again somewhat flawed.
And finally 38 Studios, for a brazen and interesting new IP which sadly may never again see the light of day despite showing a lot of potential.