CNS is being phased out for the most part, and in many states the term CNS isn't even legally protected.
As for NP vs PA:
Everyone (especially here) will tell you to become an NP because of the "autonomy." While this sounds good on paper, it really only comes into play if you open your own office or contract. The overwhelming majority of NPs work in the exact same setting as a PA - that is, in a hospital or under a physician in a private office. In both of these cases, the autonomy aspect doesn't matter, and for the most part the PAs and NPs will both be able to function similarly.
Education between the two, however, is vastly different. I wanted to be an NP - but I looked into the curriculum. Over half of the classes are fluff and theory. Very little medicine is involved. No gross anatomy, immunology, etc. One pharmacology class, many of which are taught using undergraduate textbooks. PA school on the other hand is practically medical school lite - many of the same classes, all clinically relevant, little to know theory or fluff.
If you do NP, if you want a solid education, you must go to a reputable school with a strong curriculum, and percentage-wise there aren't that many compared to the fully online, for-profit schools
. PA school is much more standardized and you will likely recieve a much better education.