I tend to disagree somewhat here. Comparing past greats in football to today's greats is apples to oranges when considering the size differences, let alone training methods. Boxing however, has set weight classes. So a welterweight from the 80s is the same size as a present day welterweight, and there isn't much difference in the "sweet science", it is what it is. Football schematics have changed drastically over time, but boxing is still boxing, it hasn't changed much, if at all. It is much easier and more accurate to compare past with present. That being said, we can only speculate.
The 80s were definitely the heyday of boxing, especially the lower weight classes where Leonard/Hagler/Duran/Hearns were all active at the same time, being pit against each other multiple times. Would absolutely love to see some AI generated round-robin tournament with Mayweather and Crawford thrown in, add Canelo, Pacquiao, and maybe Julio Caesar Chavez, Pernell "sweet pea" Whitaker, or a Mark Breland and let 'em duke it out. Now that would be something worth the price of admission.