PDF editor? I have always regarded pdf as a terminal file format, the place data goes to die. Only half joking but pdf was always the final form from some other program, the internal editable data was never pdf. I have never seen a program works on the pdf directly, Probably because I have never had that much exposure to adobe software. the few times I have needed to do so I had to use a pdf programing library.
If you mean desktop publishing software that outputs a high quality pdf scribus works fairly well.