Nintendo are not really a developer, considering they have some twenty different studios, but they are brilliant, all 20 of them...
I'm going to be annoying and say Santa Monica
Seriously, though, they are good. Same with Capcom and Konami. Ubisoft used to be good, but they seem to be going the way of EA lately. Prince of Persia is awesome, though, the best game they have released since Splinter Cell: Chaos Theory.