Instead of looking at radio stations, you should be looking at which shows to advertise with. The top three user rated shows are; Cadillac and Dallas, Cindy and Ray, Denny Radio. This will be a much better use of your dollars.
There are alot of good radio stations in atlanta. it ultimatley depends on what type of music you like. I listen to 95.7 which switches around to different styles but you will mostly here country. Hopes this helps.