Nintendo Valve Square Enix Capcom Hal Laboratories Blizzard Irrational Games Rare Ubisoft

From most to least favourite. Fumito Ueda (ICO, Shadow of the Colossus) Yasumi Matsuno (Vagrant Story, Final Fantasy XII) Treasure (Ikaruga, Gradius V) Intelligent Systems (Advanced Wars series) Atlus (Shin Megami Tensei series) United Gaming Artists (Rez) Keita Takahashi (Katamari series) Clover (Okami, Viewtiful Joe) Hideo Kojima (Metal Gear Solid series)

1st Tier Squaresoft (not to be confuse with Square-Enix) Capcom Konami 2nd Tier Rareware Nintendo Team ICO 3rd Tier Activision Blizzard Ubisoft

Nintendo, Valve, Capcom

Woooooo go Valve! I feel instant kinship with anyone who holds affection for this company. It's particularly uncommon in a forum like this, dedicated to console gaming :p

A few fun facts about Valve: whenever a game is finished, the company pays for a vacation to Europe for every team member. The management structure is very relaxed, and the "leaders" aren't really supposed to be seen as higher-ups compared to lower end developers. For example, the two founding members' official descriptions are "game tester" and "Mister Awesome."

In general, I have enormous respect for any company that won't release games until they're absolutely satisfied with them. Blizzard, for example, scrapped an entire million dollar game in the Warcraft series that was 6 months away from release, because the management agreed it wasn't up to Blizzard standards. Nintendo is famous for this, and Shiggy is quoted as saying (translation): "A game postponed until later can be good later. A game released now is bad forever." Valve operates under the same mentality. This is precisely why I pick these three as my favorites: while their games are all in my top ten, it's their particular design philosophy that separates them for me. 

Yes, Valve is a truly amazing developer. I can tell that a ton of work goes into each game, and yet it seems like a very personable company. Because their games need to be perfect, it does mean lots of delays for games like Episode 2 :(

But I'm always happy to wait. I didn't play the first Team Fortress much, but I'm really looking forward to TF2. And especially theirs and Turtle Rock Studio's Left 4 Dead. My friends and I are waiting on the edge of our seat for this game.

And who could live without a headcrab hat?
 

only one person mentioned the giant elephant in the room:sony sony is my favorite dev. they are trying to be creative from every department. not just having a single genius do their work and everyone else just rehash stuff (it starts with an n). not saying that nintendo is bad, just sony is doing more for the gaming world overall. other than that there are too many that are great. listing my favorite is all i should do.

Team Ico is a specific Sony developer, by the way. They were mentioned on several people's list (including my own). I personally have zero interest in any other Sony game/developer, and it looks like lots of other people agree.

And I'd add that Sony isn't exactly the "elephant in the room." They may be big to you, but they aren't to everyone. On every list here, I think to myself: "How could they not include Valve?" But I recognize that it's personal taste. They're very big TO ME. Similarly, Sony is very big TO YOU. If there was a real, completely objective "elephant" to be named, it would be EA. Their profits, revenue, and games sold dwarf those of Sony. The only companies that come close are Nintendo and Activision.

now that i looked harder i see some sony devs. that still doesnt allow for them to put all of nintendo than. same thing. can you put all of ea for a ea canada (wouldnt though)? or t2 for rockstar. even se is on a bunch of lists. if its a rule than it should be universal. if that the case than i cant choose a best dev.

Sony as a game developer usually doesn't even cross my mind...

EDIT: " that still doesnt allow for them to put all of nintendo than." It's funny, because some people don't seem to realize that Nintendo makes pretty cool consoles, and then goes and MAKES the best games to go on that console, all within Nintendo. It's very impressive to me.

We're allowed to include Nintendo among these other developers because they actually do make games at Nintendo.