they were all ripped getting on shredded (hearns was as welterweight). Hearns < Leonard and Hagler looked like they had single digit body fat pecentage. i know duran beefed up a bit as he got older and went up in weight. he looked ripped against leonard and in his earlier fights deffo reckon hearns got down to 6-7 when he was a welter. Hagler had great ginetics for body building. he was ripped and had great muscle shape and thickness around every body part.
Duran was probably 11-13 Hagler was probably 10-11 Leonard was probably 9-10 Hearns at 147 was probably 8ish. Don't listen to people who drop numbers 6% or below. . That is dangerously unhealthy, and no athlete would be able to perform at such a low level of body fat.
Duran was never in spectacular shape post-135. He grew into a 147 fighter and his lifestyle outside the ring, eventhough he trained like a dog, made it impossible for him to be tip top by fight time. Hagler always looked incredible. Hearns was better at 154 and 160 but he looked ripped to shreds at welterweight, just like Sugar Ray.