I vote for Emet, as we saw in the manga, he was able to show himself superior and was able to send Warcury back to Marygeois in addition to making him return to his human form.

@Conker7991 Well Joyboy's haki helped him send back the Gorosei. But he was able to damage Warcury on his own which Luffy couldn't do. His weakness might be his facial area. Oda is the kind of person who would pull that kind of stunt tbh. But can't say until we have actual proof.