Having birthed with a midwife and attended a birth as a coach with both a midwife and an OB, there's no comparison in quality of care. A midwife takes the time to know you, know your plans, and stays with you a huge chunk of the time you are in labor. SO if you need to try a different position, get up and move, need some coaching, encouragement, to discuss options,etc. the midwife is there for you. Most hospital midwives work with/under OBs and immediately page them if you need them. They also spend ALL their professional time doing prenatal and birth care -a s opposed to OB's who do a variety of ob/gyn services
Birthing with an OB, in most cases, works like this.
You go to the hospital, nurses set you up and then leave you alone for a while. A doctor "pops in", checks you vaginally, looks at any monitors, then leaves. The nurses stay with you for the most part, but may of may not give you any coaching, so if you and your DH don't notice that you may need to be moving around, change positions, etc, then nobody suggests it. You may end up stalling or something and not have the expertise to know how to address it. Also, if you are in labor during shift change - usually 7 am and 7 pm, but other times also, the nurse will leave and you will get a new nurse, even if you are in the middle of pushing. SO you may end up with a nurse you have no rapport with at a very intense time. Every hour or so, the doctor pops in, asks the nurse or maybe you how things are going, then leaves. Occasionally checks you vaginally. If she/he doesn't like how your labor is going, they may push meds like pitocin or push for a c-section, but won't stay int he room for longer than maybe 15 minutes, so don't actually obserrve your contractions, how you're handling them, what sort of support you might need. When you start pushing, the nurse will notify the doc, who may or may not come. THe nurse will watch you push, giving you some instruction (but without having the masters degree that midwifes have, just probably lots of experience witnessing births). When the baby is ON your perineum, maybe 2-3 pushes from coming out, the doctor will RUSH in, there will be a flurry of activity all the sudden, probably freaking you out a bit. You'll push out the baby. The OB will hand them off, deliver the placenta, congratulate you and leave. If you were in labor for 12 hours, you might see him/her for an hour or so. DOes that sound like excellent care to you? The OB who delivered my SIL's last child never even said her name.
A midwife will stay with you, give you QUALITY coaching, help you have the birth you want, and negotiate care dcisions with you. You will feel like you have an ally and advocate.
BTW - I've NEVER heard of an OB who performed or read the 20 wk ultrasound. They take a while - like 30 min. - and an OB is generally not going to take the time to do that themself unless it's a tiny little practice. You generally are sent to an ultrasound tech who takes all the pix and measurements, then passes that on to the OB or midwife - both of whom interpret her notes. When I was "late" and had to have non-stress tests and ultrasounds, my midwife did do those ultrasounds (to measure fluid). When my midwife didn't get the numbers I needed, she sent me to her ultrasound tech to give me another chance to avoid induction - I doubt an OB would have given me that chance.
Good luck - have your DH do some reading, and have him go to your first midwife appointment and ask the midwife questions. If he's not impressed, I'd be surprised.