There are a number of doctors out there so which is the most complete doctor to have? Internal medicine, family medicine etc. What is the best doctor to have as a pcp? How do you determine which doctor is best for you?

Family Medicine. Family medicine doctors specialize in you! they take care of people from birth until death and deliver babies. Your care from a family doctor is provided in the context of your bio-psycho-social situation. About 90% of things you need a doctor for can be provided by a family doctor with continuity of care over time and a strong therapeutic alliance!
PCP. Everyone should have a primary care physician to get regular check ups. Eating healthy and exercising is fundamental to staying healthy yet a pcp to get regular check up and screening exams is of added benefit to all.
Everyone . Everyone should have a primary care doctor to help care for their basic medical needs. The people who do this are: family doctors (kids and adults), internal medicine (just adults), and pediatricians (just kids). All of the people in these specialties have been through rigorous training and who you see just depends on your preference and who you "click" with. The best way to find someone is to call your insurance company and get a list of doctors in your area that accept your insurance and are accepting new patients. Then from that list, you can ask people you know who they see and like. You may also want to check and see if the doctor you're seeing is board certified - i attached a website below in which to do this. You may meet a few doctors before you find one you really like - and that's ok. The right one is out there.