Certainly not the best moments in the trilogy, but here are my favorites from each movie:

I-Luca's eyes bulging out of his head while he's garrotted. There isn't any uglier face you will ever see than that one.

II-Sonny's kids laughing because "Daddy's fighting again!" in the flashback scene. I love kids and that scene is exactly what a kid would say in real life.

III-Neri yelling, "Mikey, over here!" during the hotel assassination. I laugh when I hear that because just think about what would happen to any other human being on Earth other than Neri who would dare call the Don "Mikey".