For me it is Blizzard. While I Love Starcraft 2 the company is a mess since Activision got them. Diable 3 has the DRM problems and was not very good compared to Torchlight 2 and WoW lost innovation and meh. Blizzard is alright and I still somewhat like them but ever since Activision they are different
Another one is Jagex. This company I loved during the glory days of Runescape 2003-2007 then they went down and is now a microtransaction company and I can not stand them anymore.
What company you loved went down the tubes?