I'm not sure if they're available for your area, but the National Geographic Trails illustrated maps are what I'd recommend if you can only have one map. The trails are colored by use, numbered, and rated for difficulty. They are grid lined for UTM. If you have a GPS, you can change the coordinates to display UTM which makes finding where you are really easy. Trails Illustrated Hiking and Recreation Maps - National Geographic Store
I'm really into maps. I have the nat geo series for most of the southern Appalachians, as well as many 1:24,000 topo maps. You can order these from the USGS. Rather than order, I buy them locally at the ranger station.
If you have a GPS, you can download free topo's to it from gpsfiledepot.com
These are the electronic version of the 1:24000 topo maps, and I use these in combination with my paper maps.
You'd be surprised how many people I meet in the Cohutta's that have no clue where they are, or which way to go.