toss up between Naughty Dog and Bioware

Seeing the more popular developers have all been listed multiple times, so I'll give a honourable mention to Grasshopper Manufacture, Shadows of the Damned is amazing, it deserves more attention, Fatal Frame IV and No More Heroes are pretty awesome too.

Valve and From Software both made classics that I will be playing for gen after gen. So I guess I'll go with Valve followed by From.

Naughty Dog and Sucker Punch (I love inFamous).

Nintendo EAD Tokyo and Kyoto created a game that re-defined the 3D Mario Franchise (Super Mario Galaxy 1/2) while getting some of the highest critical response last generation.
While also being responsible for game changing, audience widening titles such as Wii Fit/Plus and Wii Sports/Resort. Games that, quite possibly, defined the Wii experience for many people. (And spurred many, many knock-offs due to their humungous successes in the gaming industry.)
All in all, Nintendo was great up until the last year/s of the Wii.

However, I don't see any of that pizzazz that you guys see in Naughty Dog. I feel that the Uncharted series became quite bland (which is arguably their biggest franchise.) And yes, I have played them (1 and 2, to be exact.)

Honorable mention would be The Pokemon Co. seeing as how no one listed them, yet they have made many great entries into the Pokemon series all while recovering from the GameBoy Advance blunders. (Even though R/S are my favorite games in the series.)

Have you played The Last of Us?

Naughty Dog - The Last of Us and Uncharted

Retro Studios - Metroid Prime and Donkey Kong Country. Also Mario Kart 7 if you want to consider 3DS

Bethesda - Oblivion, Skyrim, and Fallout 3

Bungie - Halo 3, ODST, and Reach. Still arguably the best FPS after a decade.
Turn 10 - Best rated racing series this generation with Forza

Epic Games - Gears of War, Unreal Tournament 3, Shadow Complex, Infinity Blade, and Bulletstorm. Kickstarted the 7th gen with Gears as well as having the most popular engine. Unreal Engine.
.
Infinity Ward - Call of Duty 4, Modern Warfare 2, Modern Warfare 3. Redifined the FPS genre and have went on to selling well beyond 50m copies.

Valve - Left 4 Dead ,Portal, Dota, Half-Life

Rockstar - GTA, Red Dead Redemption, LA Noire, Max Paine

Bioware -  Mass Effect, Dragon Age, Star Wars.

Not in any specific order. And im sure i missed plenty as well.

No. That is why I didn't mention it.

Really, though, I don't see what all the fuss is about. The game doesn't seem that compelling, to me.

Hard to say. The top ones, for me, were Monolith Soft, Retro, Blizzard(without counting Diablo III), Square-Enix(handheld only), Nintendo EAD, Remedy, CD Projekt and Bungie.

Bioware for me.

Mass Effect is one of my favourite franchises of all time at this point, and not just in terms of gaming, but it's also one of the greatest sci-fi universes ever created. Add to that the stellar Dragon Age: Origins, and Awakening expansion....they've been on point this gen (minus DA2 of course, but that game was obviously rushed by EA).