So I am still really torn about what to vote for when we get there. Like Sun King says, to me it's between Pangoro and Reuni.
Pangoro almost gets the win for me just because the hilarious interaction between Parting Shot and Magic Bounce on M-Sable. I thought the Hammer Arm set was worthless, but looking at it a 252 Jolly Speed Pangoro can outspeed some key 'mons at 354 speed at +1 (Keldeo, Latios, Terrakion, M-Tyranitar, Diggersby, M-Gyarados, Mamoswine, to name just a few) and snags some OHKOs with his dual STABs. Gunk Shot is a huge blessing and a great coverage move that lets him check certain fairys like M-Altaria and M-Gardevoir (if he's at +1) or Azumarill. At +2 he outspeeds Greninja and he has a good chance of beating Gren one-on-one unboosted even if Greninja ditches its Dark Type and/or runs Low Kick. He can use Expert Belt instead of LO thanks to the good coverage of his moves, and that will help stop him from getting worn down so badly.
He still has some problems though. Birdspam laughs at his speed boosts, he's badly outgunned against Lando-T even at +1 attack, and he lacks the power to break through some serious defensive pokes (namely Sylveon, M-Slowbro, Gliscor, Zapdos, Skarmory, M-Diancie, and Clefable). There's also some fast 'mons that can revenge kill him even at +2 (M-Sceptile, M-Aerodactyl). Of course, you could argue that it gives Pangoro some unpredictability since an Adamant bulky attacker Super Power sets kills many of those defensive walls at +1 and only needs 20 speed EVs to speed creep standard Clefable. He could also easily take a different coverage move (Ice Punch!) to crush some of his other would-be counters. Overall he's just really cool and I really, really love the options and unpredictability he introduces into the meta, even if his Parting Shot trickery and hopes of picking up +2 Evasion from Defog or +1 speed from Sticky Web are all mostly pipe-dreams.
Reuni - I did indeed dream this up as a way to help TR teams. It dawned on me that currently the only 'mons that learn both Trick Room and a momentum move are base 100 speed 'mons, and I wondered if having a "fast VoltTurn" under Trick Room would help the team preserve and gain momentum. I figured that the Life Orb Nuker with Magic Guard or Assault Vest pivot with Regenerator options would just be a nice bonus, but the posts so far have shown that this thing would actually be amazing at those jobs despite its crummy typing. I'm super pumped that one of my suggestions is gaining traction and I think this is the more competitive option...but it is a lot less fun than Pangoro. I think I'm leaning towards Panda for now, but we'll see if there's other thoughts before voting starts.