To be completely honest - my memory for films is terrible, so I struggle to remember why I loved many of these. Also, many of them take unexpected twists and to say why I loved them so much risks ruining part of the surprise. I've watched countless documentaries and in order for them to make this list I have to _really_ enjoy them, and for the most part they require no interest in the subject matter in my opinion - they're just objectively good. So, I'd recommend literally any to start with, but with all that being said, some favourites amongst the favourites:

The Crash Reel - an amazing tale of a person preparing for the olympics, with an unexpected turn and just a very heartwarming/impressive journey - very very highly recommended.

The Cove - follows a whaling event that happens every year, and exposes the savagery of it. However, it's filmed almost like a thriller, in how the team set up to expose the event. Very eye opening, if a little sad, but very very good.

Drew: The Man Behind the Poster - just an amazing documentary about a man who makes amazing film posters - incredible, you'll see that he's responsible for so many recognisable posters from your childhood.

Being Elmo - lovely film about the puppeteer behind Elmo - really heartwarming

13th - very good film about racial injustice in the legal system.