Hahaha, good to see some oldschool Trigun Mafia love. =)
I had a blast hosting that game and if I could wipe everyone's memory clean and re-host here with the new crew, that'd be fun as hell.
As far as what I'd probably enjoy replaying the most, that's a really tough call.
FFVII is probably the most balanced multi faction setup that I've seen and has good variety potential, esp. with the Amnesiac (<3 games with balanced amnesiacs). Def. would be a good pick.
Harry Potter mafia would be sick just because of all the different item/character combinations that could have occurred and other related room events. Again, the roles lead to a lot of potential variety in how the game plays out so it really fits the bill.
The original SSBM mafia by Drab would also be a really fun setup to replay, though Mass Claim would definitely have been broken as hell in retrospect. If I could wipe my memory of the game and replay it with a no claiming restriction then that'd be ******. Definitely a fun setup that I wish I got to play more of. (Died on night 1 in my first game D=)
If I could also host another game again with a clean memory slate from the players + design tweaks, it'd be Bad Idea Mafia, hands down.