mine was also an easy choice as my family and i know him personally and he was my pediatrician when i was younger.
most pediatricians offer prenatal visits to go over some things and talk about what will happen in the hospital, ask questions, etc...i would schedule one of those with each doctor and chose based on that.
Mine was a very easy choice I have a primary doctor who also practices family medicine. So, I have been going to her for a couple of years but didn't know she was a family doctor. I have a separate OB because I had no clue that she could do my OB services, and then deliver and care for my baby afterwards too. I love my OB so I haven't given her up, but my primary has provided great care to me so I know she will for my baby as well.
My advise is to have an interview with them both. Let them know you are trying to choose a pediatrician before the baby comes along. I did that with mine and love him very much. Most pediatricians will give you 10-15mins at the end of their day and if they dont then how much time do you think they are going to give you when you have a sick child or have concerns about their well being?