Al Capone was really one of the top guys in American organized crime. He was the kingpin of Chicago at his time, and he made more money and was more succesful than his mentor Torrio ever dreamt of. One of the downsides was that his reign only lasted a few years.

Luciano also made huge money, but he was also the unofficial capo dei capi of the Sicilo-American Cosa Nostra. He worked with some of the brightest people ever in the world of organized crime, such as Maranzano, Lansky, Adonis, Costello, ... and his role played much longer than Cpaone's.

So: Luciano.