It's really up to you, and the care you receive varies with each specific practice. I started with my regular OB/GYN but was unhappy with the wait times and how difficult it was to schedule appointments, so I switched to a midwives practice. Though I did like my OB, I greatly preferred the personalized care I received from the midwives - it felt like they really took my preferences into my consideration, and didn't rush me out the door. Due to a move I actually went to two different midwives clinics, and had similar experiences with both. I had been a bit skeptical that they might be a little to crunchy granola for me, but there was surprisingly little pressure for alternative therapies and going natural. I wound up getting an epidural and then a c-section, and my midwife was very understanding and supportive and encouraging without making me feel judged.
I would recommend using a practice that's associated with OBs and a hospital so you don't have to worry about switching if your pregnancy becomes high risk. After talking to the other moms in my baby class, one of the things I liked the most about using a midwife is that she was there with me constantly throughout labor. The other moms said they only saw their OBs for a few minutes and then when it was time to push, and often they were left entirely alone while nurses were attending to other patients.