From everything I've heard, North Fulton is much better. I was in the process of switching practices and hospitals (from Northside to North Fulton) for my second child, but I went into labor before I was able to switch over. I was switching because I was trying very hard to have a VBAC (vaginal birth after a Cesarean), and I didn't think my OB at Northside was going to give it a fighting chance.
My doula highly recommended Margaret Strickhouser, and midwife who practices there. (Someone else mentioned her as well.)
Anyway, from what everyone says, the whole staff at North Fulton is more supportive about your birth choices. The only firsthand account I can give you is the experiences I had with the birth preparation classes. (For my first child, I took the class at Northside, and for the second child, it was at North Fulton, and it was soooo different.)
The Northside class focused SOOO much on anesthesia and drugs, as if no one in their right mind would NOT want to be lying on their back, feet in the air, tangled up in various tubes, as long as they had that epidural. They said very, very little on the side effects of any of the meds, and NOTHING about the patient's rights to question the doctor about anything, even things that were controversial, like routine episiotomies. (This was just a few months before some research came out saying that routine episiotomies tended to cause more problems than they solved.)
The North Fulton class was taught by a woman who was an R.N. as well as a doula, and talked more about different kinds of births, waterbirth, hand-and knees, lying on your side, medicated and non-medicated, coping with pain,
and how to minimize interventions. Tthe fact that they offer a water birth option tells you a lot, even if you're not personally interested in that option.
I know that "factory feel" that one other person complained of at Northside. If it's busy and delivery rooms are in demand, you might feel the pressure. Add to that how long it takes to see a lactation consultant compared to how quickly (some) Northside nurses are to force you to supplement with formula. I had some pushy nurse at Northside barging into my room without knocking and telling me she was going to give my baby a bottle of formula if he didn't tinkle in the next hour. The kid wasn't even 24 hours old yet!
To be fair, I think Northside has a more attractive lobby with prettier art. :-0