My favoutite developers:
Nintendo (although, since the Wii came out they made only one decent title and a lot of bad games... im not giving up on m yet)
Square (i mean, they have to be credited for making the FF series one of the most consistenlty good series ever, and for being responsible for golden times on the SNES with some of the best rpg's ever made. Their consistency on making good games probably makes them the best developer imho.)
Namco (for making my favourite fighting game, and some pretty decent other games :))
Midway (their games arent always good, and hardly ever very "deep" but i can enjoy shallow games like Mortal Kombat and Rush a lot... not every game in my library has to be world changing as long as it is fun to play).
Capcom (they made some of my favourite games ever, i used to be a huge megaman fan, megaman 1, 2 and 3 as well as Wily's revenge and Megaman X1 and 2 were absolutly awesome)
Worst developer:
Davilex (dutch developer)... i honestly cant think of any developer that even comes close in terms of creating unplayable smack (for those who dont know: check Knightrider, or A2 racer, DONT BUY hahaha).