I actually am an NP, so I admit bias.

I think it's best to find the provider with whom you feel most at ease. If you're the kind of person who would never feel comfortable seeing anyone other than a physician, you should see a physician.

But NPs and physicians vary tremendously in their backgrounds, areas of expertise, and bedside manner. There are plenty of awful NPs out there, just as there are terrible physicians. There are good schools and there are mediocre schools. I have four degrees, 12 years of school, and 11 years of practice under my belt. There are some NPs who have far less educational and clinical experience--but that's becoming far less common.

As far as supervision goes, this varies by state law in the US. In about 20 states, an NP can practice on his or her own; no physician is required. In other states, NPs have varying levels of collaboration or supervision requirements. But this assumes that the collaborating or supervising physician is both competent and available. Just because a physician signed the chart doesn't mean that the physician made the right call.

Scope of practice questions are self-regulated. So there are NPs who are far more experienced than their physician colleagues in mental health issues; others not so much. I think it's a terrible idea for someone with a background in diabetes to be managing psychiatric concerns! That's a law suit waiting to happen!

Some NPs limit themselves (or are limited) to the simplest of cases: sore throats, etc. Others manage multiple, complex illnesses, perform minor surgical procedures, or specialise in particular areas like HIV, heart failure, or traumatic brain injuries.

Just be sure to ask questions... the same way you would for a physician. Where did this person go to school? How many years has he or she been in practice? What are his or her areas of expertise?

I think it's also helpful to look on practice web sites. Look to see if you have any common ground with one of the providers available to see you.

I have a GP who is totally miserable. He spends about four minutes (or less); no vital signs, no history, no exam... he just sits behind a desk. I think I could have a stroke while sitting in front of him, and he'd never notice. (Yes, I'm looking for someone else.)

Incidentally, you'll find more NPs called "Doctor" due to the massive rise in doctoral programs for nurse practitioners. Some of these programs are pitifully weak; others are profoundly rigorous. So if you are going to see a doctorally-prepared NP, find out where he or she went to school. Was this some sort of lukewarm, do-it-yourself diploma downloaded as a pdf? Or was it an accredited clinical doctorate from a major academic medical centre?

Above all, find someone you trust. Find the clinician who listens, who returns your calls, who sits down when talking to you, and who is thorough and thoughtful in his or her history and physical exam. Everyone deserves that.