Is it better to get nursing prereqs filled by AP credit or take courses in college?Which is better for GPA or admission to nursing school?

AP credits are just credits. You don't get a grade transferred so those classes don't impact your university GPA one way or the other.  While AP credits can help you graduate faster, the content of a high school AP class may not technically fulfill the expectations/requirements of a particular BSN program.  I would strongly advise you to research that before assuming that any AP class would be accepted as fulfilling a BSN admissions requirement or that that class would prepare you sufficiently for the next level of course in that subject at a university.

AP credits don't affect your GPA.  You don't get the grade recorded on your college transcript, you just get the credit hours.  You can't get all of your nursing prereqs out of the way with AP classes, but it's fine to take as many as you can.  Some of those are going to be courses you can only take once in college, and you'll want to do well in those in order to improve your chances of admission.

You can certainly get some general ed courses out of the way through AP courses. However, you're still going to have to take some chemistry and biology in your nursing program, if you're talking about a bachelor's degree. Many universities now will give you their own test before giving you credit- they're suspicious of AP courses, since high schools push them on sophomores and juniors, and then dumb them down so they are not really university level. Take a lot of math- you'd be surprised how much nurses use it.