I don't think he was overrated per se. I think he was the product of his times and succeeded within the confines of those times. He expanded what Torrio left him and he did it well. The fact that they had to get to him via income tax pretty much says he had set up a solid enclave around him personnel wise, and made the right moves with politicians, judges, cops... Again, ego brings him down gunning Moran's men in a massacre, increased scrutiny, etc...

My Top Five:

Luciano
Gambino
Accardo
Lucchese
Patriarca

I have admittedly a bias on the people who "create" organizations rather than just build up from them.