I'm in no way a PBF fan. But the real answer to this is "WE'LL NEVER KNOW AS IT NEVER AND WILL NEVER HAPPEN".
Ray Leonard and Tommy Hearns are more of a sure thing against Floyd than Sugar Ray Robinson?? I'm gonna just go ahead and assume you didn't see Robinson's name on that list. As for Duran being a certain thing, no way. If Esteban DeJesus could beat a prime Duran, Floyd would sure as hell have a decent shot.
The only 2 on that list he'd lose to for definate are SRR and Hearns.. People will argue the others on both sides.. I'll ignore the ones like Winky Wright and ****.. Floyd's not a 154 fighter in my opinion.. Even though his talent would see him beat many at that weight..
Notice how you had it Hearns at 154 and not 147??? PBF could beat some of those guys, people should support the greatest fighter of there generation. He is top 5 P4P post War era as you can't really inlcude anything before the 40s
Tszyu was the guy I felt would be dangerous for Mayweather, prime for prime. Just a great style matchup. Anyone who was willing to give Tszyu time to pick his punches was gonna taste the right hand. Great hypothetical fight. So close to happening as well. Oh well Damn you father time.