Activision is the most evil in that it not only does everything it can to abuse the industry and the consumers, but openly praises itself for doing so. It's a destructive, malevolent force at this point.
EA is the most suspiciously inept of the big companies. Not to say they can't ship a product, but they're mishandling EVERYTHING lately. Not even in a greedy way; they seem to be doing everything they can't to sabotage the work of their developers. It's mind-bogglingly bad operating, but it's not evil. It's just incompetence.
Ubisoft, judging by recent events is the most spiteful.
So Activision is the dark overlord that rules with an iron fist and a penchant for genocide, EA is the bumbling moron of an evil henchman that ruins everyone's plans by accident, and Ubisoft is the stubborn child that sticks its tongue out and takes its toys away because it didn't get the last piece of cake.