Rachel was more evil, to me, because she SUCCEEDED in making Kermit give up, where Richman didn't really manage. I do wonder what would have happened to Kermit if Dani-el hadn't appeared though. I'm guessing that eventually Piggy would have gone out to get him and taken over the situation, similar to her role in The Muppets.
When Rachel tells Fozzie he smells like a burnt couch, and tells Kermit that he ruins people's lives...That is Evil.
When Tex has a little dance around his office and cuts out the power...Not so much.