Jason Isbell is my personal favorite out of the 3. Seen Stapleton and Isbell live, not seen Sturgill live, yet. They're all amazing artists, so much better than anything else that country music is producing currently. Thy're not about theatrics. People drive me a little bonkers when they say no good music is being made today, and have no idea who Isbell, Sturgill, or Stapleton are.
If you want some new, good Outlaw era country, try the Highwomen. Amanda Shires (Isbell's wife), Maren Morris, Brandi Carlile, and Natalie Hemby. Album just came out, a good listen.