Everybody's heard of Inception. It's that one movie about "a dream inside of another dream". In reality, the movie is much more complex and emotional than that. Though I won't go into details so you could enjoy it yourself!
If I had to choose, Inception would be my top 3 favorite movies of all time. I love the theme and its unique take on it. Since the movie is centered around dreams, the action scenes always look stunning.
Admittedly, this movie has an insanely convoluted storyline. It took me several rewatches and copious amounts of Google searches to understand what was going on. It was worth it though, at the end.