That is a good question and one that I had a lot of difficulty with as well. In reality, it's hard to kniow where to go find the information where "the best" professional is in any occupation, particularly the medical field.
In your local community, you could ask you trusted friends and co-workers who they have used and the pros and cons of each doctor. Particularly those that are in the medical field. Believe me, the nurses that work in the hospital setting know who the good docs are and bad ones as they see the results, failures and responsiveness of each doctor. You can ask the state medical board about claims and allegations either via internet or phone. I have seen web sites on "how your doctor stacks up" but I've never have used them so I couldnt speak to that. Your family doc that you have trust in is in the know who would be good for you.
Once in the clinic, you instincts will tell you if this is a person who cares or they appear burnt out and too busy. You want someone, who not only knows what to do medically, but will get out of their bed at midnight (if warrented )to help in a crisis if need be. In other words, they will do the right thing. Having someone take the time to answer questions is important. If they dont have time to do this on a consistent basis, then what makes you think that they will have to take care of you in time of need.
And, as a many here on VR will attest, dont hesitate to get 2nd opinions. Sometimes 3rd. It may take several visits to different docs to get someone that you feel comfortable with.