I love documentaries! I'm a sucker for ones on "classic" celebs - Marilyn Monroe, James Dean, Jim Morrison, Janis Joplin etc. I love true crime and watch 20/20, Primetime, Dateline almost every week. The Manson Family and other famous crimes (I was scared of hippies in my childhood due to the Manson family, so I thnk this is my adult way of controlling the fear! lol). Documentaries on sexuality and human interest. Cryptozoology as well - give me something on Sasquatch, Yeti, Loch Ness Monster etc and I'm glued to the TV!
One specific documentary I didn't see listed here is "Crazy Love". An odd story about a couple who date in the 50s and break up. He throws acid in her face in revenge. Years later they marry. Very weird but fascinating.