I agree that GF 1 & 2 are the best and probably will never be topped!!!! . But I've learned to "never say never" in life.
However, saying that, it's been over 25 years later and I still haven't seen a "gangster" movie, (Or possibly any movie) that excels in every aspect (Direction/Producing/acting/musical score, etc.) that comes anywhere near exceeding the GF.
"Mankind must put an end to war before war puts an end to mankind. War will exist until that distant day when the conscientious objector enjoys the same reputation and prestige that the warrior does today." JFK
. But I've learned to "never say never" in life. 
