I have been searching as well. Atlanta itself seems to be pretty dry when it comes to real gyms. We have way too many fitness clubs.
Madhouse gym in Mableton seems to be the best around. Rise in Oakwood is also good, NLO compound in Sugar hill (the old metroflex).
I go to Onelife, it’s a fitness club but it’s way better than a LA or Lifetime.
I need to find something near the north perimeter of 285