Sorry to resurrect an old thread, but I'm really amazed that you hadn't seen the Godfather yet, or Goodfellas. I'm not a big fan of Scarface myself, but that's not really a 'mob' movie anyway. Anyway, if you haven't seen it, check out Godfather II, I personally prefer it to the first one, as DeNiro has a role as the young Vito Corleone. The first one's a classic though.

You can't really compare it to Goodfellas, as it's a much more modern, action filled movie. Plus you've got Sorvino, DeNiro, Pesci, Liotta. I'm gonna go get the papers, get the papers.