There are a few for me.

Chrissy: He represents the modern day up and coming wiseguy. Has the hot girl, nice cars, completely ruthless and a drug addict. That role was VERY realistic

Pauly: Old timer still looking for the respect he has never gotten.

Joey Peeps: Again like Chrissy, a young enforcer and collector for his capos. Portrayed it so well that I have researched to see if he was connected in real life.

Layy berese: Well, the guy just got pinched for being a loanshark for the Gambinos, how much more realistic do you need?

Carmine Lupertazzi: GREAT depiction of a boss in my opinion

Least realistic:

Tony: James did a superb job playing the role, the writers are to blame here. No way does a real life boss do the things he did. I.E. be involved in every racket personally, be a lonashark, kill a capo in his own crew with his bare hands, etc

Silvio: Probably my favorite character, but just not real life material in my eyes.