XSEED games/Marvelous Entertainment are probably my favorite publisher, because when they localize a game they localize it RIGHT. They also pick up games that most wouldn't, are very welcoming towards fan feedback, and come on... They've published YS, The Last Story, Pandora's Tower, Ju-On, Fragile Dreams, etc. Awesome games that were probably not making their way to the west without them or Rising Star Games.
Bandai Namco, Nintendo, SEGA, and Square Enix have all published many of my favorite games. And so has Capcom! But the latter has done some incredibly off putting things.
Developers wise.... If Tri-Crescendo are still active, then they're my favourites. The few games I've played from them have left a huge impact in me. Baten Kaitos, Eternal Sonata, and FRAGILE DREAMS are all works of art that have a very, very special charm that you'd be hard pressed to find somewhere else.
Again, Nintendo/Bandai Namco/Capcom/Square Enix have all developed some of my all time favorites, and I'll always hold them dearly for that.
Special mentions: Gamefreak, TOSE, Hall, whoever developed the Twisted Metal games, which wasn't Sony.







