Haha, I made a very similar thread before you did. Anyways, Pulp Fiction is the most explosively original and witty of all of these- although Godfather is an incredible technical achievement. I like all of these films to some degree, although Brian De Palma has the least inspiration in the bunch- the Untouchables is not great.
Of what I've seen, I enjoy The Departed the most. For some reason, the film has grown on me the more I watch it and it has become a favorite of mine. (I didn't enjoy the original Infernal Affairs film much though)
Goodfellas just edges The Godfather for me. The Godfather is perhaps technically the better flick, but I would rather watch Goodfellas any day of the week!
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“It takes considerable knowledge just to realize the extent of your own ignorance.”― Thomas Sowell
I’d probably give The Untouchables a higher rating than most here. I think it’s really fun movie and, as someone else described it, the closest to De Palma’s Star Wars as we got.