Brian Deer's 2004 documentary "MMR: What they didn't tell you"
It's an investigation on basically the father of Anti-vax sentiment/misinformation, uploaded to YouTube by Brian himself.
I am honestly very disappointed by documentaries in general. Rarely do I find them informative enough or not biased. They are generally made for the masses who know 0 (or even less than that?) about a subject.
If your goal is education, I suggest a book or a course. Now, for motivation and just "time wasters", they are fine.
The one documentary I watched and enjoyed was alphaGo. It was nice feeling the stress of the match and seeing how they handled it, the setups and whatnot.
The Century of the Self, a multi-part series on the Genesis of contemporary US Public Relations and propaganda, politics and the godfather of it all, Edward Bernays.
Watched it once 20 years ago and still think of it in reference to many broken business, government and political approaches.
I really liked "small brained american" travelling from Ireland to Japan (on a motorcycle). It starts slow and kind of boring in the UK but the later parts are so good. Less commentary, just showing life. He is visiting "dangerous" countries like Ukraine, Iraq and Myanmar, but focussing on the normal people's everyday lifes, while being a "small brained american".
PBS NOVA is great. That playlist has 20 documentaries on it about a range of topics, most just under an hour long, one that is just under two hours long.
Everything from the chanel -> History Time. Pete Kelly is an awesome story teller and works really hard on making in depth historical documentaries, some three hours long.
The Fog of War w robert mcnamara. A fascinating and honest telling of the vietnam war from one of its main architects. In it, the guy basically admins to committing war crimes. Not big on history/war documentaries, but this is one that really made an impact on me and changed the way I see the world. Not depressing or gory, at least I didn't think it was.