Wiping out classic Harley would probably also wipe current roller derby hyperslut Harley as a side effect. Worth it.
Jenny is high octane waifu but doesn't compete with Gwen's loli DFC, Frankie's older sister/babysitter/milf-ish vibe, or Raven's everything.
Frankie is, sadly, replacable with a number of other red-heads. She will be missed, but her loss is something we can cope with.
Comes down to Gwen and Raven. It's a hard pick, but I think I have to keep Raven. Several versions of Gwen are downright fugly. I don't wanna live in a world without Greythighs.