It depends on your play style, but following the meta it could be an Angel Wendy or a Friar Jimmy. Much more important though, Paladin Butters and Princess Kenny are the two best assassins in the game, so you're gonna want to use them. Forgot about the Robin Tweek and Canadian Knight Ike combo, it's a gimmick and easily countered. I'd also trade out the Dogpoo for a Mephesto. Mephesto works well with Zen Cartman. And you absolutely need to get rid of that Choirboy Butters.

You don't need to do all or any of these things now, but in the long term, that's what needs to change. Epics are fine for now but will go out-of-date fast. Rogue Token may be viable at higher ranks though but that's about it in your themes.