Yeah, Heat is kinda border line. I can think of several other movies that are too, but still good films.

As far as best mafia movie. That's really tough. Each film is a different story, so I guess it's what you're in the mood for watching.

I voted Godfather 2, just because I love Robert Deniro's role as Young Vito.
Then again, I really like his role as Jimmy Conway in Goodfellas. Ahhh decisions, decisions!