The Facehugger jumping at Kane makes me jump, consistently, every single damn time I watch the movie. Alongside the blood test scene in The Thing
, which also always makes me jump, I'd say that there's an argument for it being one of the most effective jump scares in movie history.
Also, the scene with Ripley and Newt locked in the room with the Facehuggers in Aliens
is so intensely unsettling and anxiety inducing.
So yeah... I find the Facehuggers to be scary.