#3 Kenny Omega wins
AEW's website lists Moxley as 1-1-1 overall and Kenny Omega as 5-4 overall. With Moxley already taking part in an Unsanctioned Match against Joey Janela at Fyter Fest, his record isn't as full as Omega's. Moxley also missed about a month due to his staph infection, so the fact is that he only has three bouts under his belt in AEW.
Omega has had a high-profile match almost every week on Dynamite and rightfully so. AEW management made this match unsanctioned and therefore it won't count towards overall records. That won't matter to Moxley and Omega. Regardless of who wins, they'll still have the right to say they beat the other man.
The most straight-forward finish in these types of matches is one man winning by pinfall or submission. Omega has still been going through his issues in singles matches, and he obviously needs a win.
Moxley needs a win as well, in order to solidify his standing as one of the top guys in the company. 'The Cleaner' could easily hit the One Winged Angel and pick up the win. Things could spill out of the ring for the majority, but a pinfall win is still a victory over the other man, records not withstanding. A win at Full Gear could also start Omega on his potential path to a title shot, depending on the plans for the title post-PPV.