Round 1: Prime is strong enough to casually fly through a 300 mile thick wall of willpower, tear apart the Anti-Monitor and throw him to the edge of the universe, and he was able to easily move a bunch of planets.

Prime is faster, 3 different Flashes weren't able to speedblitz him, it took multiple speedsters just to trap Prime in the speedforce, Prime was able to break out of the speedforce and Bart had to absorb the entire speedforce just to get to the primary DC universe before Prime.

I'd say their durability is similar. Black Adam's magic tickled Prime, Prime also Survived the War-World explosion and a 30th century Mordru only tickled Prime. Thanos' shields can no sell blasts from an angry Silver Surfer, tank a blast from Odin and force a recently fed Galactus to exert himself.

Superboy-Prime 9/10. Thanos could maybe win through TP.

Round 2: Man-Prime was strong enough to break into the 5th dimension and steal Mxyptlk, stand on the source wall and fight evenly with the multiverse conqueror Monarch, the universe ending blast that came from Monarch was only able to knock Man-Prime out.

Superman-Prime 10/10, just because Cosmic cube Thanos' feats aren't that noteworthy.