The question of this thread would be more awesome if you include the other final bosses such as The Savior, Sanctus, Arogax Arius, Abigail (DMC movie) and Arkham (final transformation). But even if you include all of them, I already got the answer who would win. Simple, the Demon Emperor, Mundus.
Why? Its because his abilities and powers could destroy all of them just a few seconds evidently from what he did to one of his loyal servants, Griffon. Mundus cast a deadly massive electrical spell upon Griffon with no mercy and pure suffering before his death. So imagine Mundus cast a spell like that to every each one of the villains within the DMC universe. Just a blink of an eye and they're gone for good. Done. Lol!
Also, Mundus is the strongest DMC villain ever in DMC history evidently that Dante have no choice but to transform himself into his father's ultimate devil trigger, the legendary dark knight, Sparda, to defeat Mundus. Tell me, which other DMC series that Dante transforming himself into Sparda to defeat the final bosses? I don't think none of the series except DMC1 of course. That's basically shows that Mundus is the toughest enemy that Dante ever face in his life.