It's tough for me to pick one singular favorite. It's tough for me even to pick 25 or less favorites.
The best I can do is limit myself to picking 12.
My list goes a little something like this (in no specific order):
1.) WarGames — Birth of the age of personal computing meets Cold War doomsday clock.
2.) Scent of a Woman — It's nice to have a bit of that antiquated concept of integrity.
3.) Paper Moon — A humorous take on the characters in the American Midwest who suffered through The Great Depression.
4.) The Breakfast Club — I'm not sure if there has ever been any other film that combines sociology and anthropology at the micro level and psychology at both personal and group levels any better than this scintillating gem.
5.) American Beauty — The typical dysfunctional, suburban middle-class American family.
6.) The Passion of the Christ — I watch it every time I think things can't possibly get any worse for me, i.e. when I'm thinking the grass is greener everywhere but my neck of the woods. (Thank You, precious Jesus Christ my Saviour, for loving me.)
7.) Cool Hand Luke — For all of us who march to the beat of a different drummer, so to speak. For us who don't like to play by the rules when we have questions about who made the rules.
8.) The Outlaw Josey Wales — I thank God for the brave Americans who fought to survive in the lawlessness of The Reconstruction in the Southern U.S.
9.) Tie, Quo Vadis and Schindler's List — The chronicle of the birth of my Faith; the horror of the nightmarish way a charismatic, Satan-worshipping, demon-possessed madman was able to camouflage himself under my Faith's cloak and forever scar it.
10.) Roots (miniseries) — See my description of number six above.
11.) Event Horizon — Just for the hell of it.
12.) Three-way tie: Traffic, Deep Cover and Training Day — Why the U.S. Drug War is a farce, and the prison-industrial complex a sad reality that the U.S. federal government will never admit.