Luciano, this topic has come up many times. You can do a search and find many opinions. Here are mine:

Close Fit:
Johnny Fontane = Frank Sinatra: Washed-up, teen-idol crooner with fealty to the Mob; role in war movie puts him back on top; sluttish, movie-star ex-wife.

Hyman Roth = Meyer Lansky: Jewish adviser to Mafia; “always makes money for his partners”; tight with president of Cuba; started out as a truck mechanic and got connected during Prohibition; fled to Israel and South America to escape Justice Dept.

Moe Green = Bugsy Siegel: Pal of Jewish adviser to Mob; “headstrong, talking loud, saying stupid things”; “city he invented was Las Vegas”; “someone put a bullet in his eye.”

Johnny Ola = Vincent (Jimmy Blue Eyes) Alo: “Sicilian messenger boy” to Lansky [N.B.: Name is an anagram.]

Joey Zasa = Joe Columbo/John Gotti: Meucci Society = Italian-American Civil Rights League; “Best-Dressed Mobster”; publicity hound; shot at Italian-American event.

Rosato Brothers = Gallo Brothers: Renegade faction in Mob family declares war on Don (Joe Profaci); Joey Gallo recruits blacks and Hispanics while in jail; “leave the gambling for last.” [N.B.: Eldest brother Larry was garroted in the back of Brooklyn’s Sahara Lounge after-hours in 1960 and was saved by a NYC cop who happened by—the basis of the Frank Pentangeli-Rosato Brothers scene, but with roles reversed.]

Stretch Fit:
Vito Corleone = Frank Costello: Most powerful of Five Families; “had all the judges in New York in his pocket”; primary business was gambling and unions; retired after being shot by rival mobster. [N.B.: Some fans believe Lucky Luciano was the model because he arranged for the death of Joe “The Boss” Masseria at a restaurant (in the book, Vito Corleone arranged for the death of “Maranzalla” at a restaurant). But Luciano dealt in prostitution and drugs, was convicted and sentenced to 40 years in jail, and was deported. Vito Corleone deplored prostitution and drugs, and never went to jail.]

Emilio Barzini = Vito Genovese: Tried to kill rival to become Capo di Tutti Capi; attempted to make move on drugs at gangster convention (Apalachin). But: Genovese died in jail; Barzini was killed.

Frankie Pentangeli = Joe Magliocco: Weak successor to strong Don (Profaci); beleaguered by rival faction (see Rosato Brothers/Gallo Brothers); attempt to move against stronger Don backfires. But: Magliocco died of a heart attack, Pentangeli turned state’s evidence and killed himself.

Peter Clemenza = Frank Labruzzo (Bonanno Family): Top capo to Don (Bonanno) stayed loyal to son of Don (Bill Bonanno) during gang war; philosophical bent. But: Labruzzo died of cancer before being permitted to form own family. [N.B.: Richard Castellano played Labruzzo in the TV movie, “Honor Thy Father.”]

Sal Tessio = Gaspar Di Gregorio (Bonanno Family): Top capo to Don (Bonanno) betrayed Don and son by siding with rival Don (Stefano Maggaddino) in return for being named head of his own family. But: Di Gregorio died of heart attack; Tessio was taken for a ride by Willie Cicci.

Fredo Corleone = Thomas Gambino: Weak son of Capo di Tutti Capi is passed over, given “legit” businesses to run. But: Garment Center trucking is not a “Mickey Mouse nightclub”; Fredo was killed after betrying his brother; Tommy is still alive.

Luca Brasi = Willie Moretti: Legendary strong-armer; “can do a job of murder all by himself”; “most valued friend” of Joe Bonanno and other Mob bosses; killed by the Mob (probably Vito Genovese). But: Moretti was killed by agreement among several Dons because his tertiary syphilis was causing him to become loose-lipped.

No Fit:
Michael Corleone. No son ever successfully succeeded his father as Don, much less surpassed his father--and endured over the long term. But: Salvatore (Bill) Bonanno was being groomed as his father’s successor until the “Banana Wars” caused his father’s retirement and Bill’s imprisonment on credit card fraud charges. Also: John Gotti designated his son as Don, but Junior wasn’t even able to run a phone-card scam successfully, was not accepted by many factions in the Family, and went to prison.

Tom Hagen. No non-Italian has ever served, officially, as a Family’s consigliere. But: Meyer Lansky was unofficial consigliere to all the Five Families and several out-of-town mobs; Jake Guzik served as Al Capone’s mentor and business manager.