Most underrated: Carlo Gambino / Frank Costello
Most Overrated: Vito Genovese.

Gambino ruled for 19 years, never went to jail, and died at home. He was low key and outsmarted a lot of people. His leadership was never in question. His borgata was stronger when he died than when he got it.

Costello was smart and diplomatic. He ran the family for 20 years as either boss or acting boss, and built a gambling empire with political connections that provided protection. He wisely let Genovese take over and "retired" with his gambling interests and was out of the limelight. He died at home a very wealthy man.

Genovese inherited a powerhouse when Luciano went away. During his tenure at the top or near the top, he had Gerard Vernotico murdered so he could marry Anna, was involved in the murder of Carlo Tresca the publisher, had to flee to Italy, faced murder charges when he came back to the US, got sued by Anna for financial support, called for or arranged for Apalachin, got convicted for narcotics, and pushed Valachi into ratting. That's a lot of newspaper headlines and instability.

In my opinion, Genovese was the same train wreck as John Gotti. Genovese and Gotti committed very similar mistakes: exposing LCN (Apalchin and the weekly meets at the Ravenite), pushed people into ratting (Valchi and Gravano), personal murders (Vernotico and John Favara), highly publicized atempted murder / murder of their predecessor (Costello and Big Paul) and narcotics.