My preference is a 7'-6" 2-wt. But that is just me. Most of my Smokies fishing is during the spring, summer, and fall when fish are active. So, I rarely break out the 4 or 5 wt for the mountains except in late fall, winter, and early spring when I will be throwing big heavy indicator rigs.
Just my opinion.
These kinds of questions are asked on here all the time, and the variation in responses is always very wide. Each person has their own fishing style, and it is in your best interest to try and find out what your style is and just go with it.