I was just watching some development videos on Starhawk and I was surprised to see that Sony Santa Monica's logo was shown at the begining of the clip and it went on to show that they had a big hand in helping LightBox Interactive with Starhawk. That got me thinking, Santa Monica has been Sony's go to studio for all their development needs, they helped out with Little Big Planet 2, they collorborated on Warhawk and now Starhawk, they had a hand in all the God of War PSP games (and the mobile game), Sony send them out to help other developers with bringing their games on to the PS3 and they also develop the main line God of War games. They seem to be the most useful studio in SCE's line-up.

Others may argue that Naughty Dog have created more IP's and have currently created a bigger franchise for Sony, that Japan Studio release much more content and run PSN or that Cambridge is their go to team for things like research, non-game software development and Home.

I personally think that Santa Monica is their most useful studio. Second Party studios can be included in the discussion.

I don't know enough about Microsoft and Nintendo, but I'd guess that Rare and EAD Group 5 (boring name) are their most useful studios.

hei your right there are always news that santa monica studios are involved!

I would have just said Polyphony digital, as their games have the highest sales, but your right!

Also I would add the Japan studios because they made the Engine that is used for example in Demon souls, and lot of other games.

The Sony-family-developers may have the best relationship/partnership in the whole industry. You dont hear this from other console-manufacturers

Its very difficult to see wich one is the most valuable from what we know

I'm pretty sure Santa Monica is mentioned in the opening screens of Flower and Fat Princess. But theses people may not exactly be the same guys as on the GOW team.

Team ICO may be a bit in the same situation as they're part of the Japan Studio

With Nintendo it is very hard to say as they have several 'massive franchises' such as Mario, Pokemon, Zelda, Wii... and Mario Kart.

I'll pick EAD 1 as it does Mario Kart and Nintendogs, both instrumental in the DS' success.  But I would understand if someone said EAD 2 or EAD 5 though.

well MS and Nintendo and SONY have different Internal strutures, Nitendo have there own Massive Internal Super Studios, SONY have there massive Global Network of Studios, and MS have there almost failed SONY type global network they have seem to been closing down most of there studios to now an small group and instead of buying studios like Bioware they bought Skype for overpriced 8.5 billion. 

The most valuable studio for SONY is Naughty Dog, they helped Create the Playstation brand with Crash Banicoot and now PS3 with Uncharted as the face of the PS3. SONY Santa Monica can be reguarded equally as important, but hey they are both in Santa Monica anyways :D. 

Nintendo has there internal studio

MS had Budgie who are now departed from them, so i can only say there most valuable studio is the team who is making the next call of duty. 

Activison has the call of duty teams, i would say NeverSoft since they created Tony Hawk and continued Guitar hero but they aren't getting the attention deserved by activison and should just be placed on call of duty as well. EA is its Fifa and Madden Studios. Ubisoft with its Montrel for AC. 

Sony's most important dev team in my opinion has to be naughty dog. Here are the reasons why

The orig crash games made the playstaion very popular.

Jak n Daxter franchise sold well.

Every Uncharted game has done better than the one before it.

They helped with

God of war 3, Infamous etc.

I might be biased though because they are my fav devs.

Nope, your not biased, it's true.

Naughty Dog are very valuable to SONY, the Uncharted games are not only some of the best games this gen, but they are some of the best looking aswell.

They also supported SONY in the past with Crash Bandicoot etc.

They are owned by EA and i doubt they would sell Bioware who is one of there best developers.

Bioware was bought by EA but MS had the Chance to step in and out bid EA but they didn't, which was an bad mistake because no franchises like Mass Effect is going to PS3 and they missed out on exclusive titles such as Dragon age. 

For Sony, their most valuable dev has to be Naughty Dog. They made one of the PS1's biggest games, Crash, and made Uncharted. Their games are contant million-sellers, and set the standards for PlayStation systems. They are better than SCE Santa Monica.

For Microsoft, I woud say Bungie, before they left, so I guess Rare would do.

For Nintendo, it would either be EAD3, or Retro Studios. Both of them produce chart-topping games, and have the talent to take on anything. EAD3 made some of the most beautiful games Nintendo has ever produced (Twilight Princess), while Retro made Metroid Prime, so that's a tough call.