I'll always bet the house and everything in it on Saad! Miracle Matthew at his peak always finds a way.
I felt that way about prime Ray Leonard, then came Montreal Duran, felt that way about Thomas Hearns, then came Ray Leonard fight #1. The lighter weights have been much more competitive than the heavyweights, and have many more ATG's that probably could beat beat another ATG prime vs prime at any given time. So the only one I'll lean to as almost undefeatable in his prime was Ali between 1965-1968. There hasn't been a heavyweight yet I believe beat that version of Ali.
I meant of those fighters who fought in the SMW divison. I don't engage in cross era fantasy fight predictions, way too many unknown variables, in this instance including, but not limited too - Do we give these guys the benefits of PEDs too? If so, how effectively will they take to them? How will they react to dehydrating for the day before weigh in and rehydrating for the fight? We have no way of knowing. How will fighting twice a year only impact their performances? How will much greater wealth and fame, much sooner in their careers affect them? That's enough to make predictions pointless, imo. For what it's worth, based on what they achieved in their own era, Charles, Moore and Tunney appear higher on my all time p4p rankings than RJJ.
Jones would pummel Conn and Tunney unmercifully. Likely Foster, too. He was so much quicker to the target.