More DeNiro, less Pacino; always a good thing.
Still, again I think No. 2 was best for a variety of reasons ... Coppola's direction was incredibly strong, the acting was perfect throughout the cast ... but mostly because of the way it meshed two incredibly compelling stories, young Vito in the old days and Michael Corleone in the '50s. IMHO, some of the more compelling stuff in Puzo's book was how Vito got to be Don Corleone, and DeNiro has certainly done some worthy stuff in the 30-odd years since that movie, but I don't think he's ever topped his performance as young Vito.
No. 1 is a marvelous piece of movie-making, though.