The first 2 Godfather movies own. The third one wasn't as good. Goodfellas and Casino are awesome mob flicks as well. Donnie Brasco is good, but is a step or two below GF and Casino.

Scarface is overrated. If you want to see a good gangster movie with Pacino in it, go watch Heat. That movie is a masterpiece. Another good DeNiro flick is Ronin.