Out of this list, I would say Godfather 1. Godfather is an excellent movie; the baptism scene is iconic on it's own. The acting is superb, as is the story. I like Rocky and will watch when I see scrolling through the program guide. But it's not at the Godfather's level.
For me it's not movies I hear I should watch. It's TV shows. I don't binge watch and I've missed lots of good TV shows or so I'm told. For example, the Office, Parks and Rec, Breaking Bad, Game of Thrones just to name a few.