My fave is A4125, an amazing low to mid speed road with more than enough undulations, curves, ups and downs to keep anyone interested. It also has hardly any cars on it in my experience.
Then for a real blast you can finish off up or down the A4067 with around 1/2 mile of forward looking visibility on much of it.
I think I must have been up and down those 2 roads about 15 times this summer alone.
Edited by Nev, 25 September 2014 - 11:27 AM.