In terms of quality, choose a doctor who is board-certified, who has attended a reputable medical school, is experienced and has admitting privileges at a JCAHO accredited hospital. You should also select someone with whom you feel comfortable.
Also consider how busy the physician is and the quality of the office staff. You don’t want to wait weeks for an appointment, interact with a doctor who doesn’t have time to answer your questions or deal with rude office staff.