I'd rank an attorney higher, but perhaps that's my personal bias. Or it could be the graduate education, ongoing legal training, and the duty of competence, recognized as an ethical imperative and as a basis for civil liability, that attorneys have. Remind me again, please: what happens if cops give bad advice? How much time do they spend researching the legal issue you present them with?
If you want legal advice, seek out an attorney. I'm not saying that a cop's input is not worth knowing, if nothing else it tells you something about their disposition, but by no means is it the highest authority you can get prior to dealing with a jury. Advising a client so that they don't end up before a jury is unquestionably a job for a lawyer.