Let's Scare Jessica to Death (because of the extremely creepy, oddly dreamlike quality to the filming) and Black Christmas (because it never explains itself) are two of my favourite horror films. (Mind you, I also argue that the only good horror movie sequel is Halloween II (because it simply continues the same night), so you may use that to weigh my judgement.)
(Mind you, I also argue that the only good horror movie sequel is Halloween II (because it simply continues the same night), so you may use that to weigh my judgement.)