Ask 5 contractors what the best system is and you will get 5 different answers. My advice is to consult a licensed contractor who will take the time to learn your personal comfort levels and design a system to match. Ask to see a manual J heat loss / load calculation to prove the equipment being offered is the correct size. Run away from any HVAC contractor that will not provide a load calc, it is the only way to properly size a system.
In the North GA area your two most popular systems will be gas or heatpumps, both will work well in your area. I would suggest a piggyback system, a gas furnace with a heatpump. The heat pump works until you reach a pre-determined outdoor tempature (balance point) at this point your heat pump will not be able to keep up with your homes heat loss. When Balance Point is reached your HP shuts off and the gas furnace is brought online. get a nice air cleaner as well, Honeywell F300...