Tough to narrow it down, but these three beat out a handful of others by just a little, if only because I've never NOT enjoyed a game by them:
Intelligent Systems (Advance Wars, WarioWare, Paper Mario, Fire Emblem, Tetris Attack, Mario Kart Super Circuit)
Grasshopper Manufacture (Killer7, No More Heroes, Fatal Frame IV, Contact, Flower Sun & Rain)
BioWare (Baldur's Gate, MDK2, KotOR, Jade Empire, Mass Effect)
"'Casual games' are something the 'Game Industry' invented to explain away the Wii success instead of actually listening or looking at what Nintendo did. There is no 'casual strategy' from Nintendo. 'Accessible strategy', yes, but ‘casual gamers’ is just the 'Game Industry''s polite way of saying what they feel: 'retarded gamers'."
-Sean Malstrom
