Do you have kids? Only because schools
are a big deal depending on the area so I thought it might change my advice for you.
None of those areas are bad really. It just depends on what you are looking for. Do you have sometimes keeping you from living inside the perimeter? (besides money... haha). Just trying to get a better feel for what you are looking for.
I'm more familiar with the north and west areas you are looking at. I can't provide much info about Buford. Johns Creek is a good area, for sure. Dont discredit the Marietta area, too. Especially East Cobb, which has real nice houses and great schools. The Acworth/Kennesaw area can be tricky because traffic is a BEAST on I75 these days. I actually moved away from that area in order to get away from it to an area thats in every other way less desirable so I can do down and hit I20 and avoid I75 all together. (For example, working night shift, I would leave at 5:!5 most evenings to sometimes be late clocking in at 7pm. That was terrible. To be clear though, I was working at the CHOA campus thats inside Atlanta near the CDC).
I have worked at CHOA for over 6 years now and think its generally a pretty good place to work. I have heard pretty good things about Northside as well. As far as the CHOA campuses, they are the same company but different in a lot of other ways. Egleston is a teaching hospital where Scottish is not. Egleston has the cardiac kiddos and SR does the rehab stuff. As far ad EDs go (if thats what you really want to do), i can't provide much insight but I think they are both probably fine.
Hope this helps. Good luck.