Honestly, Activision, EA and Ubisoft tied for me.
EA and Activision for general douchebaggery, and being a corporation before a games publisher. Pushing the same crap forward year after year ain't making me like you. TBH, EA is presently worse in my books so long as Blizzard remains relatively ok whilst a part of Activision. Once Blizzard is gone, EA wins for having generally a better focus towards PC with their games, and the two become tied thanks to killing companies I loved in the name of business.
Ubisoft must die for the DRM and general distasteful attitude towards PC players. I will never knowingly purchase a Ubisoft game whilst this keeps up, because of how hard it will be for me to enjoy it.