Very simple at the height of each other's power who was A- Making the most money. B- Exerted more influence over all of LCN. C- Overall the most powerful boss.

Simply put I don't think there was any boss more powerful than Luciano. He had all of the future bosses in his pocket that he was able to control and lead big egos and violent bosses. Carlo's intelligence and cunning I feel like where unmatched but he didn't have the power to do what Luciano was able to do which is why I believe Luciano was the most powerful.