1. Ring - I really didn't know anything about this film going into it, which is the best way to see a horror film. All I'd heard was it was a scary Japanese film, which seemed extremely exotic at that time, when DVDs were just starting to leak out from other countries. I had to seek out the DVD at Scarecrow Video (one of the best video stores in the world), because at that time, nobody else was carrying it.
I watched it in the most perfect situation possible. I was alone, it was late at night, I had all the lights off. The film was kind of slow, but it had a tension that built and built so when Sadaku crawled out of the TV at the end, I nearly jumped over the couch backwards in fright. I had never seen something so terrifying, it was the greatest movie scare of my life, and nothing has ever approached that feeling again.
The remake was dang good too, easily one of the top 5 American horror films from the last 10 years.