I guess I have a low bar but TNG Q episodes were all very funny, Deja Q if I were to say #1.

I’m an atheist though so I wont get scared by ghosts/horror stuff, but I guess the “worst feeling” moment was actualy TNG Best of Both worlds. I think the realization that the doomsday scenario is actually coming, it is real and inevitable, our chances are extremely low, the very moody soundtrack made it a very sober experience for me the first few times I watched it.