I think Ron Teufel won best abs five consecutive years in the AAU Mr. America contest. I remember seeing a Muscle Builder magazine cover of Pierre VanDenSteen displaying incredible abs.
Those guys really stood out to me.
Two great picks.
Nubret had good abs for golden era. Franco had good abs, his oblique tied in to his serratus and abs giving him a good ab pose.
For the mass era Paul Dillet had good abs.
I think the very best have all been mentioned Pastel, Priest, Tinerinno, Makkawy, Tufuel, Bill Grant.
Alot of people say Zane but his abs looked weird.