I like the route down to Montgomery to Dothan to I-10 and further east to I-75 at Lake City. I start my trip from the Birmingham area, though, so that is my caveat. I'm not coming as far as you are.
While the Atlanta route is all interstate, it is a longer distance with many steep grades (both up and down) in eastern Alabama. It takes longer but has fewer stops. I have driven it so many times (not always towing) I could do it in my sleep.
The Columbus route is more direct but offers less interstate and more stop-and-go than the Atlanta route. And since you are travelling beyond Montgomery it doesn't necessarily put you in a good jumping off spot.
The Dothan route is shorter than the Atlanta route but has stop-and-go of the Columbus route but for a shorter length. Also the first town into Florida (I think it is Cottondale) also has a community development fund supported by the local law enforcement as Jen mentioned in other towns so you need to watch your speed here. Us towing folks normally don't get going too fast but it can happen.
So it depends on what you want - shortest distance/time (Dothan), all smoother interstate travel (the Atlanta route) or the in-between route (Columbus). I have taken the Atlanta route south (assuming you are missing rush hours in Hot-lanta) and the Dothan route home.
The last three times going home via the Atlanta route I have always had a long delay between Macon and Atlanta south of I-675. No apparent reason but it has put me off that way going home.
Good luck with your travels.
Bama ED