I'm curious as to how you come to this specific conclusion, when the OP's criteria is both team and individual success? Penguins have more Cup wins and appearances.
When I think of great Penguins, I think of Lemieux, Jagr, Crosby, Malkin, Bowman, and quite a few more lesser stars that have contributed to their success. When I think of great Devils, I think of Scott Stevens, Scott Niedermayer, Brodeur, Jacques Lemaire, and maybe Lou Lamoriello (none of which really have the same clout as the Penguin icons).