From the films I've watched, the likes of Logan, La La Land, Your Name, Spirited Away, Arrival, Inception and the films from The Dark Knight trilogy are great contenders for my favorite film, but although those films are exceptional, the greatest film I've ever watched and ultimately my favorite would be Interstellar.
Simply said, alongside the philosophy behind the movie, Interstellar captured a sensation of escapism, curiosity and excitement that I've never found myself capable of receiving from any other film. Christopher Nolan is a masterful director and the movie Itself was a complete masterpiece.