I think a list like this has to be difficult to come up with...so many memorable lines...how do you pick the top 100? And you know that you will always have someone who will disagree with any or all that are selected and some will be unhappy that their favorites were omitted. That's probably true of any top 10, or top 20, top 100, the best, the worst, etc. etc.
It was a pleasure doing some cleaning over the weekend with Godfather I playing on tv. That's a movie I've seen a zillion times, but never tire of watching again and again. In fact, I liked the whole series -- even Godfather III, which was trashed by a number of critics and moviegoers. Maybe it wasn't up to the standard of Godfather I and II, but still a good film nonetheless in my opinion.
I understand the subjective nature of doing a list like this, but I think it's a safe assumption that each line should be ingrained into the popular culture, even for people who are not fans of the movie. If Casablanca was worth 6 quotes, Gone with the Wind gets three quotes, and the Graduate and Jerry McGuire each got two quotes, I find it mind-boggling that each of Godfather I and Godfather II could only get one quote apiece. Especially given some of the other loser quotes included in the top 20 of all time (particularly #s 7,9,13,14,16,17,and 19.) Are you going to tell me that ANY of those quotes was better than "Leave the gun, take the cannolis?" What a joke.