Top five, eh?

Alright then. My current top 5 as of now, in no particular order:

Blade Runner (Final or Director's Cut)
The Good, the Bad and the Ugly
Apocalypse Now (Theatrical; NOT the "redux" version)
The Usual Suspects
Abre los Ojos (aka Open Your Eyes - remade as the inferior Vanilla Sky)

This will likely change by the end of the day, and again by the time I go to bed, and again when I wake up in the morning ...

Anyway, honorable mentions that often make it into my top 5, but didn't quite make it today:

Alien
Almost Famous (Director's Cut)
Blue Velvet
City of God
Close Encounters of the Third Kind (Theatrical or Director's Cut; NOT Special Edition)
Eternal Sunshine of the Spotless Mind
The Fall
The Fountain
Groundhog Day
The Iron Giant
Kiss Kiss Bang Bang
Let the Right One In
MASH
Moon
Pan's Labyrinth
Raiders of the Lost Ark
The Road
Six-String Samurai (not so much a "best" as a "favorite," if that makes sense)
Thank You for Smoking
There Will Be Blood

Wow, that list became longer than I thought it would. Sorry about that.