Re: Which of these fighters would be the most difficult to defeat at their peak?
Here's my picks for who I'd favor, if any:
Ali: Wouldn't favor anyone. Lewis and Frazier are the best men for the job, I think. Tyson would have a decent shot.
Charles at 175: I think I might pick Spinks. Might not though. Foster and Jones could pull the trick.
Jones at 168: His opponent has to weigh in at 168 too? If so, that kind of limits things. If not, and we can just make him a full fledged Light Heavyweight (which he always was in historical terms), I'd favor Spinks and probably Charles and Foster. Conn would be interesting.
Hagler at 160: I'd favor Monzon, Robinson, Jones and maybe Hopkins. I might pick Leonard if he were to step up to 160 in his prime as well.
Robinson at 147: Wouldn't favor anyone. Leonard and Burley run him close though.
Whitaker at 135: I'd pick Duran. Several others who could do it, but none that I'd favor.
Mayweather at 130: As with Jones, if it's strictly at 130, it limits things. Still, I'd favor Armstrong, Chavez, and maybe Saddler. Match him with Lightweights, and there's a few more I'd add.
Pep at 126: Even peak for peak, I pick Saddler. Saldivar could make things interesting.