I think it would be Benevidez by decision or late stoppage. It would look a little like the Plant fight or the Andrade fight. Too big, too strong, too fast, too much. Benevidez also has a very solid chin.
Oooh - bloody fantastic fight this. I'll need to think about this, but I'm leaning Benn on points or a late knockout - I think Benn was too resilient in the long-run for Benavidez. Also, I think Benn's style would cause Benavidez hell - Nigel was a proper proper street fighter.
Benn by battery. Gavril give Benavidez fits by just pushing him on the back-foot and even dropped him. And Benn was a far classier pressure fighter than Gavril and certainly whacked a helluva lot harder.
Benavidez was like 20 or 21 years old when he fought Gavril. He quite clearly developed a lot since then. This is a low argument. It's like saying that Benn would beat Canelo because Jose Cotto wobbled Canelo... Benavidez would stop Benn late.