I post this here under Part 3 since it's probably my favorite of the first eight. I love the shadowy figure of Jason with the knife coming through the shower curtain and the 3-D reference on it.
What's curious is that the trivia here mentions how Jason doesn't actually kill anyone in the shower in Part 3 (yet he does in Part IV). All that aside, I still love it.
Here is how I would rank each film's original poster art...
Part 3-D Friday The 13th Part 2 Part V Part IV Part VI Part VII Part VIII
The posters and VHS covers alone, really put a stamp in the horror/slasher film industry. IMO, they were just as important as the movie itself, as is the "Friday the 13th" trademark title. Unfortunately, F13 is also notorious for its eras in continuity and logic, and the movie posters are certainly not immune to this phenomena.
Part 2 cover shows a shadowy figure holding an axe however, Jason never once uses an axe or hatchet in the movie. Part 3 shows him stabbing through a shower curtain, but like you said, Jason does no such thing(nor did he use a buck knife in this film) but as I recall, the lobby cards and VHS backing shows Debbie taking a shower, which leads me to believe that the poster art may have been a gimmick used by the producers to foreshadow her demise and build up tension. Plus, it was also used to show the 3-D aspect of the film. Don't ask me what the hell they were thinking with part 5 poster art, that's another story lol!!!
If there's one F13 poster I wish I could get my hands on, its the one I remember seeing in a movie rental store back in the late eighties, in which the cover shows Jason smashing through a window with a double edged axe, with each of the movie posters of parts 1-8 at the bottom. I've yet to see one on E-Bay or Amazon, so keep your eyes peeled for this one, because it's quite epic!
I don't believe I've ever seen that in-store poster either.
I also like some of the insert posters available for the early films. The posters for the first film can be a bumpy ride as many replicas exist. Not that they aren't still attractive but you have to be careful if seeking authentic ones.
I had a nice Part 6 one that I got from a video store forever ago that had the art for the other boxes below it. A poster dealer sold me a Part 5 one cheap because it was just text, but he was cool for selling one off for something like $5.00. Nice to see people still collect stuff from the 80's as that was a great time for film art. My room (as a teen) was wall to wall posters from dealers and rental locations. I still have a framed Pope of Greenwich Village that I had framed in '88.