Fedor vs Crocop is by far the best.
A HW fight will always be more significant than a fight between midgets or LWs
Top selling PPV's of all time:
Mayweather vs Pacquaio (147 pounds) - 4.6 million buys
Mayweather vs McGregor (154 pounds)- 4.3 million buys
Khabib vs McGregor (155 pounds)- 2.4 million buys
Mayweather vs De La Hoya (154 pounds)- 2.4 million buys
Mayweather vs Canelo (152 Pounds)- 2.2 million buys
* Tyson vs Lewis (Heavyweight)- 1.9 million buys
*Tyson vs Holyfield II (Heavyweight)- 1.9 million buys
McGregor vs Diaz II (170 pounds)- 1.65 million buys
McGregor vs Poirier (155 pounds)- 1.6 million buys
*Tyson vs Holyfield I (Heavyweight)- 1.6 million buys
Nice try bud...Clearly the general public doesn't care about weight, they care about skills/persona/buildup.
The biggest draws of the past 20 years (Mayweather, Pacquaio, De La Hoya, McGregor) have all been guys who spent the majority of their career below 150 pounds.