Airem would pack a big and poignant emotional punch but I still suspect it's going to be the much pedestrian option of Burnham.
Seems like the favorites to be the Red Angle are Micheal and Atrium. (couldn't resist to make fun of the most common misspellings in this forum).
Perhaps I have no imagination, but since Michael seemed to have to be saved from death as a child, she must be the one who suits up and saves the day. And maybe they'll be bold and she'll have to sacrifice herself to save everything. And maybe the moon will fall out of the sky.
The Red Angel has changed time. Thus it can't be Michael Burnham, because in the future the Angel comes from, she's dead. Or at least, that's how I understand it. I wouldn't put it past them doing an ENT-style nonsense thing where the alien Nazis start the time war from the twisted timeline that only exists as a result of the time war...
It wouldn't be the first time Trek dipped into the predestination paradox. In fact, the earliest it did so was Assignment Earth. And no one said they changed time by detonating a nuclear missile above the Earth.