...Itachi doesn't have the rinnegan and he owned Nagato, so basically all you have to possess Shisui's eyes.
Pretty much, and you will win!
Own that eye and you'll be better than anyone in the Naruto world.
So yeah, rinnegan < MS, depending on the type you possess?
[Obito] Kakashi didn't have both eyes against Nagato, If Kakashi owned both sharingans, both MS, He would have more aces! thus winning!?
MS wins, totally!