It really depends on your level and what films you're into. I could recommend some great films with lots of dialect for you to learn, but some may be too much. What's your favorite film?

"The Wizard of Oz" is amazingly simple to understand, and you probably already know the story! Disney movies are great, too. "Aladdin" is my favorite, "The Little Mermaid" is great, and "Snow White" is boring hahaha. I don't know what you like, but older movies work very well. They had to speak a little more slowly and clearly because the sound equipment wasn't as good back then.