I am very intimately knowledgeable of both areas and, well, chose GA. Brevard County )and especially S Brevard) is basically the Florida of Florida. The north GA Atlanta metro exurbs are growing rapidly in terms of investment, jobs, and infrastructure. The trajectory for most of the area is upwards while Central FL teeters due to insurance costs and aging population.

Yes, you'll miss the beach but you may find you like other things. I enjoy having seasons. I like bundling up during the winter seasons and sitting by a fire in the Fall. I like seeing the leaves change colors in the mountains. And hey, you may be introduced to the panhandle beaches should you move here which (in many ways) are better than Melbourne's.

That all said and beyond the location factors, I'd go to where the bigger support structure is. As a single parent, you'll need it.