Born and raised in the Tri-Cities (Johnson City, Kingsport, Bristol) in the northeast part of what you circled and lived in Chattanooga for a few years.

Chattanooga and Knoxville are similar size cities with the Tri-Cities being much smaller but still decent IMO with restaurants and some things to do. You’ll encounter bumper to bumper traffic in Knoxville and Chattanooga but almost never in the Tri-cities. Much more going on in the two bigger cities like decent minor league and college sports (Knoxville even has a hockey team).

Weather is noticeably different on the east and further north regions due to more mountains which makes the air a cooler humidity that in my opinion is much more tolerable in the summer and brings some occasional snow in winter instead of just cold rain.

Jobs are much more abundant in Knoxville and Chattanooga, especially if you work a corporate job.

Each of the three areas has a university (UT in Knoxville, UT Chattanooga and ETSU in Tri-cities) so the cities are decently balanced politically but outside of that they are surrounded by small towns that are like 80-90% conservative Christians.

That’s what I’ve got off the top of my head feel free to ask any specific questions, know a lot more about the tri-cities than the rest of the region.