Basciano.

Accardo? His life, what type of person he was, everything about him has been pretty well documented over the years. He's one of the more notable names in American organized crime history lol. The extent of his political/governmental connections, or whether or not he was a secret informant, are the two primary things shrouded with mystery when it comes to Accardo, but the same could be said for any Chicago boss throughout history.

Regarding Chicago, Paul Ricca, of course. You definitely have to put Lefty Campagna & the extent of his leadership within the organization during the 40s & early 50s. Things got very cloudy for the feds during that period. He doesn't get mentioned very often. Died young.

Then you have guys like Vince Solano, Skids Caruso, Turk Torello, Frank LaPorte, Sam Carlisi, Al Tornabene, of course the present day Johnny 'Bananas' DiFronzo, Jimmy Marcello, and the rarely mentioned Jimmy Inendino, who managed/have managed to fly under the radar, but were/are extremely powerful, ruthless, painstakingly quiet bosses.