You are in a challenging location. Years ago I got good reception from Tullahoma, SW Coffee Co. It's about as far away as Marshall Co. I used the largest Radio Shack combo UHF/VHF antenna (VU-190) and a Radio Shack preamp. I could get the main VHF Nashville stations and the three Huntsville UHF stations, although not 100%.
You need the largest antenna possible, as high as possible, with the lowest noise mast-mounted preamp (Channel Master Titan 2 model 7777).
You'll also need an antenna rotator.
In general I'd suggest dedicated UHF and VHF antennas (if you need VHF).
For UHF the AntennasDirect 91XG might work. See www.antennasdirect.com.
You could just give up on VHF, since the only VHF digital station is WMSV-DT in Nashville. If you can get NBC via UHF from Huntsville (WAFF-DT) you wouldn't need it. Otherwise you'd need a huge VHF antenna just for that one Nashville channel.
Unfortunately there's lots of variation with terrain and exact location.
Look around your neighborhood for large antennas. Ask what their reception is. Sometimes that's useful.