I have the CNN one (not the "America Remembers" commemorative one, but the first one) and the HBO one (In Memoriam - New York City, 9/11/01 (2002)). Both will cause you to relive the horror of that day as if it was happening while you are watching it.
9/11 - The Filmmakers' Commemorative Edition (2002) is a must-have. It's by the two French filmmakers/brothers who were doing a documentary on the training and daily life of a rookie fireman, and had been filming him for months until one day they went out to check out something on the street and a noise overhead caused one of them to look upwards - with his camera - and see/capture the first plane to strike the Twin Towers. They were right there on the scene and went into the Towers with the fire crew, filming all the while. It's an amazing film and story that I won't spoil by revealing any more.