Arya next move
teleport to KL, Kill Cersei with LF face then using her face to send troops to the north to help fight the zombies.
shareGiven the choice between killing Cersei, or having the chance to be a hero in the war between the living and the dead, she'll want to go be a hero!
Of course if Jon says that he can't win the war unless some assassin takes out Evil Queen Cersei, she'll grumble but she'll do her bit.
Cersei's on her list of people to kill, she would revel in the sweet satisfaction that would bring her.
OTOH, there are no guarantees in the battle against the dead that she'd come out a hero. As we've witnessed, huge battles are fairly chaotic affairs where anything can happen. I think she'd opt to kill Cersei, she can always join the battle later.
Of course there's no guarantee she'd be a hero, and I'm no weapons geek but I doubt her style of fighting would be effective against armies of undead. But do you think she'd pass up a chance to fight at Jon's side?
So IMHO that's what she'd rather do, but not what she will actually do.