Mondess122 said:

Black Christmas (1974)- Some people argue day and night about what the first slasher film is...and I think it's this one. It's not as well made as something like Halloween, but it's also much more stylish and moody than Friday the 13th.

I'd disagree with you in regards to Halloween. I think Black Christmas is a much more engaging film with more interesting characters and a far scarier murderer.

I do agree with your point on Friday the 13th, though. Of course, the entire Friday the 13th franchise is an exercise in derivative mediocrity, so it's hard not to.