Most
Nintendo - EAD Tokyo. Intelligent systems is real close, but they've put out some sub par
games lately, like Fire Emblem DS, Wario Ware Snapped, Super Paper Mario
Sony - Team Ico Sony has an amazing amount of talented developers that have done a lot more than team Ico, but I'm putting quality over quantity here, and their output has been almost flawless.
Microsoft - Ensemble Studios Now defunct, I know, but they made amazing games. Still really hacked at MS about closing down their biggest grossing 1st party dev.
Least
Nintendo - NST Mario vs Donkey Kong 2 was pretty cool, but other than that they have basically done garbage, and garbage ports like Majora's Mask to Gamecube. Also, Metroid Prime Hunters sucks, really bad as a Metroid game, and is still not very good as a quake clone.
Sony - Guerrilla Games Not that I think Killzone is objectively horrible, but... I still think it sucks.
Microsoft - Rare If only for how far they've fallen since GC\SNES days. Really they are still a decent developer, but MS has very few first party now to judge them against.