Team Ico, Insomniac, Nintendo, Naughty Dog, Square Enix (in that order).
I don't really need to explain for Team Ico, and Insomniac has consistantly held my attention through the 3 Sony generations. The only game I won't give a damn about is Resistance, which I guess leaves 3 Spyros, 4 PS2 Ratchets, and 2.5 PS3 Ratchets that will hopefully turn into 3.5 (Overstrike looks interesting through). Nintendo is a "no duh", Naughty Dog for a similar reason as Insomniac (minus the PS3 era), and Square tickles my "guilty pleasure JRPG" tastes.
i was going to say bethesda but then i saw blizzard/ activision and i love blizzard games and i loved CoD4 (none of the others after that though) so i had to pick them. if it werent for the activision and blizzard teamup i would have most likely picked bethesda
Insomniac who made Ratchet and Clank, Resistance, the first three Spyro games, and Disruptor which was a great PS1 title. My first game that I obsessed over was the original Ratchet and Clank and my first PS3 game was Resistance: Fall of Man, so this company has a near and dear place in my heart. Such quality games.