Leeds got into the semi finals of the CL with Rio in the team. I seem to remember Rio nearly made the WC or Euro Championship squad at 18/19. He was inconsistent at West Ham, but stepped up another level at Leeds to the extent that he was (almost) guaranteed to be a great player - Utd were not potential they were buying an already fantastic player. He absoubtly stood out a mile.
I think Maguire is a very good player and would be an improvement on what we have, but Rio was a great player in a time players like Adams, Terry, Carvalho, Vidic, Campbell played and was better than all of them. Every single one of the players I’ve mentioned below would be the best CB in the league today.
If Rio was around today, and available he would easily be the first £100m defender.