There are several flies that are "legendary" to this area i guess, however, i don't believe that you will find a fly that will catch you fish 100% of the time. I am a firm believer in confidence, the fly you have the most confidence in you will catch the most fish on because you spend more time in the water and less time changing flies. I know sometimes i will try to put on different flies that i haven't used in awhile or flies i think will work, but i spend more time changing to different flies and don't really give them a chance. I always seem to go back to the same select flies the majority of the time. Just my theory.
By the way, smoky mtn. blackbird softhackle by mr. hartsell.......................give it a shot, i think you'll like