I'd think in the south with the mentioned mild winters R 30 would be fine. Also believe that with the humid summers it'd be nice to have a more compact blanket. Surely shy away from cellulose products. I've had both in my homes and actually talked with an insulation contractor (40+ yrs exp). He prefers batts. He claims over time the blown in stuff compacts and only more can be added. Once crushed down the insulating factor goes down and difficult to add vapor barrier on bottom unless new const.
fwiw, use roll r11, and use the stud cavity (cut segments) for the transverse lays to cut down installation time.
Lastly I priced out buying insulation and for just a little more than my price he provides and installs. Benefit of buying truckloads of the stuff.