Here is a list of the best documentaries since 2000 according to the Chicago Film Critics Association: https://en.wikipedia.org/wiki/Chicago_Film_Critics_Associati...

You will also find several categories of documentary film in Wikipedia links here: https://www.locserendipity.com/TitleSearch.html?q=documentar...

Categories include:

Documentary films about the media: https://en.wikipedia.org/wiki/Category:Documentary_films_abo...

Documentary television series about astronomy: https://en.wikipedia.org/wiki/Category:Documentary_televisio...

HBO documentary films: https://en.wikipedia.org/wiki/Category:HBO_documentary_films

Documentary films about space: https://en.wikipedia.org/wiki/Category:Documentary_films_abo...