After having played SotM for a few months now, and becoming a big fan, I've come to a conclusion:
I really, really hate Spite.
Note, I don't mean in the sense of finding him hard, or disliking his fluff. Rather, playing against him is just aggressively unfun. The first half of the game is almost always a waiting game for him to flip, given how much he regenerates. The second half is boring, because there's no variation: he always has the same drugs, and always does the same things, with no card play at all. What's more, the "suffer damage every time you use a power" is just masochistic. In almost every way, Spite feels like an experiment in how to design a villain that, ahem, spites the players for wanting to play the game.
Does anyone else have any villains they really, really hate playing against, for whatever reason?