So we're still fighting the Vietnam War, even in our choice of movies. Military veterans pick Mel Gibson's "We Were Soldiers," which tends to emphasize the heroics and sacrifices of the armed forces, as the best Vietnam movie. The general public, on the other hand, choose "Apocalypse Now," which tends to emphasize -- well, the title sort of says it all.
The Vietnam movie I always recommend to everyone wasn't even in theaters. It was a 1979 made-for-TV movie called "Friendly Fire," starring Carol Burnett and Ned Beatty as the parents of a soldier killed by his own forces. An investigative reporter starts out trying to uncover whatever evil resulted in the death, and finally concludes that it was just an accident; bad things happen in war. But the parents just can't accept that conclusion, and the movie ends, as things usually do in real life, with no neat resolution. It's a painfully honest account of Vietnam with powerful performances.