I never liked jump scares. They're cheap and completely overdone. It's only good when there isn't a sound associated with it and it still scares you, or when it's something like a glass falling off a shelf, because it's not actually "scary" but it does instill a little bit more fear. You can't throw too many in there though otherwise the player will get used to them, and that's no fun. Gore is the same way. Tons of gore doesn't really work on people anymore, unless it's stuff that you haven't ever seen before (see Evil Dead; that movie sends shivers down my spine just thinking of the crazy crap that goes on), because even the casual gamer is used to gallons of blood. It has to be used in the right context, or mixed with some other terrible thing to really have a lasting effect.
Chase scenes for me never get old. They aren't permanently scary, but you freak out during the chase like no other. Outlast is a prime example of a chase scene horror game. It really freaks you out.
My personal favourite, however, is psychological horror. The early Silent Hill games, including the new P.T. and Silent Hill: Shattered Memories are perfect examples of psychological horror. The "uncanny valley" kind of stuff really jacks you up, because it takes something normal and completely turns it around on your brain so that you just naturally don't feel comfortable. There have been numerous moments in SH that have left a scar on my brain forever, most notably the strange fetus-like thing in the sink in P.T. that talks to you... nothing about that is right. That's why it's so freaky.
Creepy things are generally better than scary things, because scary things scare you for just a little bit. Creepy things affect you so much that you can't help but think of it at night. Sleeping with the lights on kind of stuff. Creepypasta is also a good example of having generally more creepy things over scary things.
Besides that, a lot of things contribute to the perfect horror experience, and I think games like Silent Hill(s) do that perfectly. Dark, morbid environments with low lighting and enclosed spaces, containing things that are "off" that make your mind triple guess itself and send you spiraling into a never-ending freak out session.