The Haunting (1963) with Julie Harris is also a long-time favorite. I first saw it in the movie theater. I was 15 or 16 at the time. Scary as hell.
That one is truly creepy and without all the blood and gore. Just the atmosphere, a few tricks and the acting is all it took to scare me.
I like “The Uninvited” because it’s a nice mix of some spookiness, some romance and some humor. The brother/sister banter was great fun.