Hard question because you can define "big" and "successful" in different ways. Capone was nominally "bigger" because his Chicago rackets, at their peak, generated more than $100 million per year--probably more than Luciano made during his peak years. But Capone wasn't so "successful": his fellow gangsters forced him to get himself arrested and spend a year in prison because of the heat and negative publicity his wild ways were generating. And he spent more than a decade in prison for a stupid tax rap that he could have avoided, and died of a venerial disease that he could have been treated for if he weren't afraid of needles. By the time he got out of prison, he'd lost everything, including his marbles.
Luciano, by eliminating the Moustache Petes, forming the Commission, and modernizing and opening up the Mafia, was more successful in making a lasting impact on organized crime. But his arrest and imprisonment for "white slavery" were scarcely less dumb than Capone's imprisonment for tax evasion. He was exiled in 1946. He made a brief comback attempt that year that failed, and his power diminished steadily after that.