Square and Atlus.

Pubs: Nintendo, SCE.
Devs: Bethesda Softworks, Naughty Dog.

Pubs: SCE and Nintendo

Devs: Insomniac and Bethesda

Rockstar: GTA, Bully, Red Dead and Max Payne

Ubisift: Assassins Creed, South Park and Far Cry

Sony and Rockstar

Too hard to choose. I'm suprised nobody said Level-5. They've made a couple of great games.

1.) Activition (For Blizzard games)
2.) Sony (This was a Tie with Capcom until I remembered Sony is publishing Street Fighter 4/Shenmue on PS4)

They also sometimes have others publish their titles. Namco would include Namco Bandia (where you would also get Tales, and the romorered PS4 exclusive will most likely be published by Sony in the US. They also don't release as many games in comparison to other developers. While they are still one of my favorite developers, the others would provide more.

Nintendo and square enix ( only for turn based ff) or Bethesda

Its got to be Sony, they have the most diverse developers under their banner
You get
The Japan Studio, team ico, Polyphony Digital, Naughty Dog, Bend Studio, San Diego Studio, Santa Monica, Sucker Punch, Guerrilla Games, Evolution Games, Media Molecule, London Studio

Naughty Dog and Capcom (old Capcom :p)