This is my favorite one, anyone else's?
I think somehow this is the definitive Friday the 13th, or if you like the definitive Jason Voorhees movie.
It happens in Christal Lake, it features the original Jason, the group of young victims are amongst the more likable of the series, and i find this better to have obnoxious dorks killed, the mood is great,the tone wasn't yet so tongue in cheeky like it would start to be around the 6th entry.
I like the cinematography a lot, and i find this tall not too bulky not too "rotten zombie" Jason to be one of the best.
Also Jason is still a big retarded know-no-better creature rather than the evil hulking decomposing corpse of the latter installments, and that's the better way to portray the character in my opinion.
Add to all this the last contribution to the series from effects and make up master Tom Savini (cleverly exploited to showcase even more of his creations having Feldman's character to be one latex mask skilled craftsman enthusiast) and you have what i consider the perfect recipe for the good old classic Friday the 13th movie.