In order, 1 being most favored.
1: The Texas Chain-saw Massacre: Any of them. I have 4 of the 5 movies on DVD, including 3 versions of the original 1979 and 2 versions of the 2004 remake. I still need to pick up the 2006 version, though.
2: Dumb and Dumber: Movie never gets old. I've seen it at least 100 times start to finish. Always find something fresh to laugh at with this movie.
3: Scarface: Tony Montana is perhaps the greatest fictional character of all time. Al Pacino at his finest, and a hands-down classic. The 1932 Scarface is pretty good as well.
4: Zombi: Great foreign Italian-gore film. A Lucio Fulci classic.
5: Megalodon: I doubt many of you have seen this movie. It was released in 2004, but I believe it went straight to video; which is funny because the special effects are amazing. This movie is about an oil rig that drills deep into the Atlantic ocean bed. The giant drill ruptures a fissure, exposing a "second" ocean filled with prehistoric life. They come face to face with the ancestor of The Great White Shark, the Megalodon - 70 ft or prehistoric terror. This thing is a dinosaur! I highly reccommend renting this movie. It is a little slow at the beginning, but that is because the script has good depth to it.