Here's some that I like a lot. As far as "best ever" goes, I don't know. But these are all great:

Westfront 1918 - G.W. Pabst
Hearts Of The World - D.W. Griffith
They Were Expendable - John Ford
Fixed Bayonets - Samuel Fuller
Attack - Robert Aldrich
Sands Of Iwo Jima - Allan Dwan
Hell Is For Heroes - Don Siegel
Days Of Glory - Jacques Tourneur
Air Force - Howard Hawks
The Thin Red Line - Terrence Malick