You misunderstand me. I'm not saying that she's not evil. She's hella evil. But she's entertaining. She's interesting. And that's why I say she's a good character. She keeps the story worth watching, as a good villain should.
I rank them on how well they help move the story along, How well they fit their role, and how interesting they are to watch. N isn't innocent either, yet we still love him. Cyn just does it bigger.