Yeah, SCE as a whole is a sketchy inclusion. Go with Insomniac, because they have had a major product ready for PS3 in three consecutive holidays, which I think makes them Sony's biggest asset as of right now. Obviously Polyphony could be on there, except it's been a long time since GT4.
The problem is, I don't think anyone here has really done the research on what games are developed by which particular studios, especially with the Japanese devs. I have NO idea what the studio breakdown is at Capcom or SE or Konami. Are Pro Evo and MGS developed in the same studio? Or is there a network of studios like EA or Sony?
I think my top 4 would be Nintendo EAD, Harmonix, Maxis and Blizzard. Those studios can invent totally new types of play, or take old types of play and introduce them to a wide audience.
And btw, what world are people living in where SE is still a mover and shaker in the "console wars"?
Some that haven't been mentioned but which had mega-hits recently are Ubi Montreal (AC, R6V, R6V2), Neversoft (GH franchise), and Nintendo EAD Tokyo (Galaxy).
"[Our former customers] are unable to find software which they WANT to play."
"The way to solve this problem lies in how to communicate what kind of games [they CAN play]."
Satoru Iwata, Nintendo President. Only slightly paraphrased.
