It occurred to me just now that all three have been criticized here and elsewhere to some degree for their biggest fights being against smaller men coming up. The respective smaller opponents Monzon and Hagler faced were far more accomplished of course at 160. That, and Hopkins' list of opponents at 160 isn't too great on the whole. Hagler seemed the most dominant of the three, Monzon had better longevity and consistency, and Hopkins gets left behind based on the edge the other two hold in those departments.
Hagler is the best fighter of them ultimately imo. Hopkins is the best technician for what it's worth imo though, Hagler's a fine technician though, and the most formidable in-fighter. Monzon isn't good technically for me, but he's got one of the greatest ring presences of all time, has fantastic timing and is a great ring general. I don't think Hopkins can bea Hagler at all. I think Hopkins has a good chance of beating Monzon. Monzon-Hagler is the most interesting fight for me, Monzon dominates the ring so well, Hagler would do well to offer movement and box at a high tempo, a la his Bennie Briscoe performance. If Hagler will fight though, and he has the abilit/speed to get off first and more often, but Monzon saps the energy of come forward men so well over the long haul with his battering ram body ahots. It's these reasons that even though i seriously don't rate Monzon technically, i rate him in terms of effectiveness and i see him as effective at all ranges. I think Monzon has a good chance of beating Hagler, but Hagler is the only one who has a good chance of winning against both of his opponents here.