They are both extremely biased. They will care only for their own "kind". Here is AMA apologizing to African American Doctors. Everybody does this; a Caucasian doctor will get similar treatment in downtown Chicago. If you watch Dr.House, imagine him to be a bunch of doctors. A Caucasian bunch one day, an African American bunch another day, a Chinese bunch another day and so on.
So the doctor you get to see is actually determined by all these boards. They will put all possible obstacles in front of the undesired skin color or religious affiliation, which will be different flavors for different regions. They will respectfully ask the undesirable to look for nurses jobs. Or screw them up during referrals. Or ask US citizen minorities to take English tests with sentences like "Jim is a six year old boy" and Questions like "How old is Jim?". Since time is money for doctors and these Test of English as a Foreign Language tests essentially delay the doctor from getting certified, these non US born doctors move on, typically to low paying rural areas in some other state or county. Where they end up encountering patients that get angry that a non-US born doctor is treating them. Talk about irony.
This does work out well for rural areas as these doctors are typically very talented. If a doctors life was based on pure merit, these doctors would be in the top hospitals in big cities. But they are not; partly perpetrated and encouraged by patients too. The urban patient gets as upset as a rural patient psychologically and the value of the placebo effect is pretty high for treatment purposes (This works against you for major diseases though. Cancer pains will return again at a different focal point).
So remember the rule: A bunch of doctors equal one bad cop. Do not let them bunch up to decide what is right for you. Their bad side comes out when they band together. And if you happen to be a doctor that is naive enough to not know this; well, now you know.