I for one, am I quite partial to the Song and Dance Man [http://www.google.com.pk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CC4QFjAA&url=http%3A%2F%2Fcreepypasta.wikia.com%2Fwiki%2FThe_Song_and_Dance_Man&ei=JIpmUeHcHInDhAe3loG4Dg&usg=AFQjCNGfJosUHCHQdnOGpJxA0olaBx8ulg&sig2=9BH-slK-URwKhtcbiIh9QA&bvm=bv.45107431,d.ZG4].
Quite sufficiently creepy and with a good build up to boot.
Another favourite of mine, one which is quite long but exceptionally detailed. The Russian Sleep Experiment. [http://creepypasta.wikia.com/wiki/The_Russian_Sleep_Experiment] The writing is really really good.
Oh and The Girl in the Photograph [http://creepypasta.wikia.com/wiki/The_Girl_in_the_Photograph]. It's awesome and good for a quick shudder.
Also, Candlecove [http://www.google.com.pk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CDoQFjAB&url=http%3A%2F%2Fcreepypasta.wikia.com%2Fwiki%2FCandle_Cove_Experiences%3A_Tales_of_the_Laughingstock&ei=k4pmUfygMtOQhQfw7IHQBw&usg=AFQjCNEs-u-9sUw7y2VCCRqm8ILbjgy2rA&sig2=HEyqT3-XhagN148v-dM6gA&bvm=bv.45107431,d.ZG4]. My first creepypasta and I have to say, I love it. I simply must say that. They won't like if I don't say that.