I've read:

"Images of America: The Chicago Outfit" not really that much to read. I found some items in conflict with others that I read about the Outfit.

"Double Deal: The Inside Story of Murder, Unbridled Corruption and the Cop Who Was a Mobster" I actually enjoyed reading this. I found Sam Giancana's (Nephew of Momo) Double-Cross an interesting but kinda slow telling of Momo's life.

"The Way of the Wiseguy " I also found this to be pretty interesting as well.

Books that I have that I haven't read yet:
"Born to Steal: When the Mafia Hit Wall Street"
"Takedown: The Fall of the Last Mafia Empire"