The Biltmore Estate Gardens grow Chester. Another variety good for southern growers is Natchez. Both are available at Stark Brothers. I have purchased from Stark for more than twenty years and have never been disappointed. They have several thornless blackberry varieties to choose from.
I got three Natchez and three Chester. Hardening them off now getting ready to put in the ground. I hope they do well. Have you every tried any of the thornless blackberry from Tractor Supply. They are same brand but a lot cheaper. Thought I might try some at my farm/hunting land.