Every dick was hand crafted by big E. They’re all imacculate in their own way. I imagine Sanguinius fit the golden ratio, whereas Russ had an absolute hammer. Perhaps Pertuarbo was unnecessarily circumcised and that’s part of why he had such a complex.

Rowboat would definitely have the generic “nice dick bro”.

Alpharius could change dicks.

Let’s see, Magnus had a bunch of extra blood vessels so it got extra red and turgid.

Primarch dick tier list!

Ferrus manus was desensitized because of his death grip grooming habit