EMS Genjutsu >>>>> MS Genjutsu and he didn't know Sasuke had MS he said a mere Sharingan cant stop him.
Ay did know, Cee established that he was using the Mangekyou just like itachi (they had intel on itachi).
I don't know why you're telling that EMS > MS genjutsu, only an idiot doesn't know that. That wasn't the pijnt Ay was making. It's about catching Ay in the genjutsu, not about how powerful the eyes are. As long as you don't look directly into an uchiha's eyes, you won't get caught, and because of Ay's speed, he was very less likely to get caught. Hence why Ay said it wouldn't work on him, got nothing to do with its strength.