That's a great fight. Idk. Jacobs is the more proven operator at MW so I'll go with him via competitive decision.
I could see Jacobs KOing him. Williams would eat punches with his face repeatedly. Jacobs can crack a bit, especially on guys with no defense.
Jacobs would be too strong and heavy for PW at 160. Paul's strength was his size and incredible reach advantage over all his opponents, but he never fought anyone that massive and powerful. I always would have liked him against Floyd though. Good luck with your shoulderroll against a much bigger southpaw with an even more ridculous reach as Floyd himself has. I would have favored PW by decision in that one.
Canelo signed to fight William's as a stepping stone and fought Jacobs as one of the biggest test of his career. Jacob's would beat up Williams.