Nagato, even though we don't know how strong Sasuke's EMS is yet, It would probably be Nagato. Because he can absorb techniques, absorb his chakra, move around quick. Sasuke's taijutsu isn't the best. He could also use the Deva paths abilities to stop susanoo and his other abilities. And I don't think that Amaterasu can work because it is a jutsu and it can be absorbed also, and Kirin too. The only way he could win is if he has a new badass genjutsu that can somehow knock nagato off his ass
well if its not endo tensai ,sasuke can just amerterastu him like itachi did but its not going to be easy despite sasuke being able to spam ,nagato seems to be the winner right now since we havent seen sasuke ems