Three from top of my head:
1. The square - it was on Netflix, may still be
2. The known unknown
3. Jesus camp
I don't know if these fall under documentary category, but I enjoyed SAMSARA and BARAKA, because of their music and stunning cinematography
https://www.amazon.com/Samsara-Ron-Fricke/dp/B00AYQNOFI/ https://www.amazon.com/dp/B00AO9NDY2