Team TOR or Legacy Sith. Sheev, Caedus, Krayt, Luke, pretty unstoppable team there. Wyyrlok and Lumia are the only others on the team that aren't fodder though, so they have that dragging them down. Vitiate won't be able to beat Sidious, but at least hold him off until one or two of his teammates wins their fights and can help out. Literally everyone on team TOR are superior to the fodder of team Legacy, so that's an advantage for them as well. However, while Vitiate < Sheev, I see him surviving well long enough for at least 2-3 of his Sith to win their fights (probably the ones fighting Nihl, Vergere, Talon, or Vurik) who should win their fights before anyone else, and would help Vitiate. TPM Sidious would take part in the "Titans battle," if you will, but get downed first, as his inferiority to both Wankatine and Vity, and with Vader and Plagueis being the only ones on-par or better than anyone on team TOR or the non-fodder of team Legacy (sans Dooku being roughly > Malak and Revan, maybe even Scourge, plus everyone on team Banite being > the fodder of team Legacy) I don't see them doing too much in this fight past Plagueis and Vader blitzing the fodder of other teams, however the fodder of team Banite (Bane, Zannah, Maul) would get downed pretty easily by either teams mvp's.
As far as the fight would go, the Titans of all teams would duke it out in a badass fight while Krayt probably goes for either Vader or Plagueis, seeing as they're above almost everyone else here, and either beating Vader or losing to Plagueis in a spectacular, long fight for both. I see him fighting Vader, it seems more like Vader to actually meet him in combat over Plagueis. Caedus most likely would go after Jadus (just feels right seeing as they are the only two here that can teleport) and that would probably go to Caedus, since it most likely would stay a Force fight with lots of teleportation-dodging going on, very annoying, but executable Caedus's win. I see Malgus going after either Dooku or Luke, probably seeing them as the only worthy fights left and wanting a challenge, and winning against Dooku in a decent fight but losing (not a stomp, but it's not a very long fight either) to Luke. Fodder for Legacy get blitzed by Bane, Maul, and really everyone on team TOR individually, so they're really non-factors here. The leftovers of each team would probably help their Titans, with TPM Sidious being dead by the time the fodders are dead, and I doubt Krayt and whoever he fights (Plagueis or Vader) would be done, or Malgus if he goes after Dooku, but he'd be done soon after. In the case he went for Luke he'd probably be dead by then, and Luke'd protect Wankatine by mopping up the remaining fodder of Banite and generally weaker members of team TOR, but ultimately get overwhelmed if he got swamped by them all, which I doubt many of the Banite ppl would go after them seeing as their mvp is dead and Krayt would still be fighting their remaining mvp. Taking into account whoever Krayt didn't fight, however, Vader'd try to take down Luke which could turn the tide for the Titans getting downed, but then it gets complicated and I'm just going to go with Banite kills off some TOR ppl with Plagueis, but gets downed eventually by numbers, and Krayt kills Vader and takes on Vitiate with Wankatine and wins then is just gg.
So yeah, team Legacy for a slight majority