Prince of Darkness does make very little sense. Even less sense if you assume that is supposed to be Satan, because . . . WTF is Satan up to, and how strange are his methods? But it has the best Alice Cooper role since Monster Dog.
They Live! is awesome, despite the wrestling, but The Thing will always be my favorite. That and Dawn of the Dead were the first two actually scary horror movies I saw, when I was young and impressionable. They did kind of ruin a lot of later horror movies for me, but it was worth it.