I've always considered Activision the worst, then EA, then Ubisoft.
The funny thing for me is whilst the former two have properties/titles i have enjoyed in the past, Ubisoft don't. They just don't seem to produce games that interest me so much, so I've never had to show any dislike towards them ha.
Where as Activision's money schemes with COD and now with their Blizzard department and this Diablo 3 DRM, It just fuels my dislike, the possibility of the notion of paying monthly subscriptions to activision for COD Multiplayer is just astounding to me. I stopped playing COD after number 4, as it just got dumbed down, fair enough but the notion of setting a precedent of charging extra for your game once you've bought it. DLC is bad enough at times, but monthly subs for an FPS... sigh
I've had Diablo 3 on pre-order for over a year now, i'm just praying they haven't royally screwed up the game with their grubby fingers and ponzy schemes.