The 1996 original. I will always have a soft spot for this one as I played this around release and it was unlike anything I'd come across before. The story, the atmosphere, the music, the sense of discovery as you explored the mansion and its surroundings - all of it was incredible. I wish I could go back and experience it for the first time all over again.
RE3 and RE2 (both originals) take second and third spot.