The 'Ndrangheta is an extraordinary organization. I seriously doubt there's a more powerful organized crime unit than them. Like stated above, they are everywhere and are able to do things most other groups can only dream of. The Russians are also very powerful, but they are split into so many different units and aren't nearly as organized as many would like to think. These units may share similar interests, but overall it's a very loose association. Other powerful organizations are the Sinaloa cartel and the declining American Cosa Nostra.