I'm not really a fan of the villains, but my son wanted them so we gave them a shot. Davy Jones is easily the most powerful of the Pirates when you're just starting out. His melee attack seems much stronger than that of Jack or Barbossa. And Syndrome is just plain OP early on. With his special ability, he can decimate everything right out of the box. The others catch up with him later on, but he's the closest you're going to get to an easy button in the Incredibles play set, which I believe is the most challenging of them all. Randy isn't anything special, but he's fun to play.
One odd thing about the "villain" pack is that playing through as a villain is a little strange if you're using them for your first play through in the play sets. For Incredibles and Pirates, obviously the end game is all about defeating Syndrome and Davy Jones. Defeating yourself as.. yourself.. is a little weird, but still fun! Even more fun is playing two Syndromes in co-op while defeating Syndrome! Triplet power! ;)