Congratulations on both acceptances! That is a huge accomplishment.
Personally, I would base my decision on a few things:
feel of the program (what kind of vibe did you get from the open houses, staff/students/faculty, school values? Can you see yourself fitting into this school well?)
location (both Philly and ATL are great cities with a lot of connections to other places. However, they are also very different cities. Where can you see yourself long term? Consider lifestyle of each city, proximity to family/friends, etc.)
cost/return on investment (If money isn't a factor, then do you. Both programs will get you to your end goal of being an FNP so I personally would go with the cheaper option to accrue less debt)
I hope that helps! The decision is ultimately yours, so choose the program/pathway that you will be most satisfied with ?
Congratulations again on your acceptance to both programs! What ever you choose will be the right decision.