IMO Wotan basically no/low diffs everybody up to old Theos, but afterwards this is how I personally see things going (not including Freedrock/the Kingslayer since idk where they place in current Arcane lore):
Old Theos/AA Acheron/7th sea PK/Hades → Wotan wins 7/10 times (mostly mid diff for Wotan)
Prime Theos/pre-Fracture Acheron/post-Hades & Absorption PK → Wotan wins 6/10 times (mostly high diff for Wotan)
AA Arthur (& WoM PK just for funsies) → Wotan wins 3-4/10 times (extreme diff for Wotan)
Creation/Chaos → Wotan wins LITERALLY NEVER EVER/10 times
I like to think that all of these characters above (besides Chaos/Creation) are in a similar tier of power and are still relative to each other, so even if Wotan is more powerful than prime Theos/Silas/the PK/Durza, it doesn’t mean he’ll low diff them and/or always beat them (and vice versa for Arthur and Wotan). That’s why I like doing this winning X/10 times, maybe some factor will change the course of one of the fights and lets the weaker fighter “win,” like Acheron psychologically breaking Arthur or causing the Fracture to not be killed by Theos (a common theme with Acheron…)