as Toyah once sang … “It’s a Mystery”

AEW have announced that the final participant in the Casino Ladder Match will be a 'Mystery Man'.

So obviously the odds are on it being a recent WWE/NXT vacancy are high, who do you think it is?
What would the 'pop' be for the following:
(Listed in some kind of order, and not based on whether I know whether their non compete is up yet!) …

Massive Pop 
Miro (Rusev / Miroslav Barnyashev) – surely the favourite to enter, compete, win, and be Mox's next opponent on PPV

Decent Pop – but wouldn't win the thing 
Erick RedBeard (Erick Rowan / Joseph Ruud) – would pop a crowd and big a big man threat in a multiman match, but surely he's better saved as a future Dark Order acolyte, masked but with obvious red beard sticking out!
Zack Ryder / Matt Cardona – the smart crowd would know his real name, a decent pop for a decent guy, can work, can compete in ladder matches and would be a decent TV main event with Mox
Drew Gulak – the most recent and thus most in vogue release, had some TV with Bryan so the crowd will know him, not a world title contender however
Chris Hero / Kassius Ohno – an indie giant, but maybe too Smark, and definitely not a World Title contender
Lio Rush – has the attitude, has the promo skills, would be awesome with Darby Allin in a ladder match, could help kick start a Lightheavyweight / Cruiserweight division, but not a World Title contender

Mediocre Pop
Joe Hennig / Curtis Axel – has some name value, but not a 'name' signing 
Curt Hawkins / Brian Myers – see above, would fit Best Friends better 
Heath Slater / Heath Miller – ditto, see above, maybe a little more than Hawkins and Axel
EC3 / Mike Hutter – got over in tiny TNA, didn't scratch the surface in WWE, but has some 'name' value
Drake Maverick / James Curtin / Rockstar Spud – but seems to still be tied up in CW Tournament

Tepid Pop

No Way Jose / Levis Valenzuela – no name value, couldn't take his 'character' to AEW

Mike Kanellis – only a small cheer if Maria joined him at ringside? 
Eric Young / Jeremy Fritz – too far gone over the hill
Aiden English – would only be recognised if he did the opera singer intro
All the NXT and WWE Development talent who never made it to TV

Quickfire round, what say you Mr Scott Keith?
Boy you've definitely put a lot of thought into this one.  Rusev would be awesome, though.