The best film should be something that you have an interest in. Watch a few trailers and select a movie you find interesting.

There is no one single "best" film for learning English, as different films can help improve different aspects of learning English. Some popular films that can help improve English language skills are "The Social Network," "The King's Speech," "Slumdog Millionaire," "The Imitation Game," and "The Grand Budapest Hotel."

Hi, take a look at my podcast here on italki called #MustWatch Series/Films. I've recommended a few films and series.