Oh my gosh, this takes me back. I went through a HUUUGE creepypasta phase during elementary through early high school. My favorite MLP one was probably Rainbow Factory, but there was also one called The Cough I think, where this plague or something had broke out and the mane 6 were hiding in the dark, but one of them coughs which is a symptom of the plague so they try to figure out who it was. I remember everyone in the comments of the story were debating who really coughed which was fun as well.
As for unrelated pastas, I enjoyed a lot of the basic ones or video game ones like Ben Drowned, Laughing Jack, Lost Silver, etc. Looking back, most weren't really peak writing, but I still enjoyed them anyways. I enjoyed some ARGs as well like Marble Hornets or Everyman Hybrid.
(sorry for rambling, I rarely get the opportunity to talk about my creepypasta phase haha)