If it were up to me, personally, I'd have the 2nd Pass end with either Dante or Demifiend, if only because they'd be symbolically fitting.
Dante, because Smash 4 ended with Bayonetta, and for all intents and purposes, Capcom is 100% back in the running after the Pythra patch.
Demifiend, because the Fighter's Pass started with Joker, and ending it with mainline SMT would be neat. That, and we've got a fallen angel and a dude who can turn into a demon, why not a full-on demon?
But those are just for aesthetic reasons, nothing based on hard evidence.