I always thought that Flex had the best combination of vascularity, striations & density of any bodybuilder that ever lived. The fullness of his muscle bellies and the lines in his upper body (back, front tieing into his waistline, etc...) were unmatched. He never had the freakish size of Dorain or Ronnie (I don't Flex had/has the bone structure to carry it), but Flex had the same fullness of muscles with a more proprtioned, aesthetic look.
I think BB was at its pinnacle in the late 80's and early 90's