I've found the public-transit comparison decidedly more mixed than a clear "SF wins". Admittedly, I lived in midtown in Atlanta, and mostly went to other places that have good subway service: Decatur, downtown, Buckhead, the airport, etc. To get to other places, the buses are kind of lame, but I wouldn't say they're any more lame than Muni's terrible buses. I did have a car, but I rarely drove; probably once every few weeks, mostly to visit friends who lived in the suburbs. In SF, meanwhile, the city is geographically tiny and yet still somehow cannot run a decent public-transit system. I can jog from the Richmond or Sunset to Caltrain faster than Muni can get me there.

I will say that the Bay Area as a whole does suburban commuter rail better, because of BART and Caltrain. MARTA has a little of it, but it doesn't extend nearly as far outside the urban core as BART and Caltrain do. Though do note that if you plan to visit the Valley, there are plenty of places that aren't that easy to get to via Caltrain.