Can't list a Top 10 as usual, but a list of some astounding non-fiction films that have pushed the envelope. After a long, exhausting day at work, these are the ones that immediately occured to me. Will keep adding to the list. 

Rain - Joris Ivens/Mannus Franken
Berlin: Symphony of a Great City - Walter Ruttmann 
Man With a Movie Camera - Dziga Vertov
Sans Soleil - Chris Marker
Night and Fog - Alain Resnais
Les Statues Meurrent Aussi - Alain Resnais/Chris Marker
Glass - Bert Haanstra
Zoo - Bert Haanstra
Notebook on Clothes and Cities - Wim Wenders
Tokyo-Ga - Wim Wenders
The Gleaners and I - Agnes Varda
Dageurreotypes - Agnes Varda
The Strange Ecstasy of Woodcarver Steiner - Werner Herzog
Fata Morgana - Werner Herzog
Don't Look Back - D. A. Pennebaker
Buena Vista Social Club - Wim Wenders
Father, Son and Holy War - Anand Patwardhan
Bombay, Our City - Anand Patwardhan
Hakob Hovnatanyan - Sergei Parajanov
Kiev Frescoes (unfinished film) - Sergei Parajanov
The Mystery of Picasso - Henri-Georges Clouzot
From the City of Lodz - Krzysztof Kieslowski
I Live in Behrampara - Madhushree Dutta
Memories of Fear - Madhushree Dutta
Skin deep - Reena Mohan
Girls Unlimited - Paromita Vohra
City of Photos - Nishtha Jain
Voices From Baliapal - Vasudha Joshi/Ranjan Palit
City Beautiful - Rahul Roy
Hawa Mahal - Vipin Vijay

M