In Scotland, there are numerous roads to choose from for me. Despite the criticism it receives, I remain a fan of the A82. Sure, it needs upgrading in places but overall, what a road. Given the right moment, it’s a fabulous drivers road and as I’ve said in the past, throughout the Glen Coe region, it remains just about the finest road in terms of scenery on the UK mainland. The A82 has some terrific bends, very long straights and sweeping curves. The A87 is also a terrific road and much what said about the A82 can be repeated here, especially the scenary. From my experience is also quiet. The A83 as already discussed is also excellent. I have to be in agreement with Gavin about it’s Rest-and-be-thankfull section. Every time I’m up in Scotland I make sure I pay a visit here and take in the views.
In Wales, I thoroughly enjoy using the B5105. This road is the perfect test for any car.
For motorways, I personally find the M5 and M6 enjoyable for much of their lengths and have no problems at all in using either. Similarly, I also enjoy using the scenic A74(M).
If I really had to limit it down to a single road, I’d still have to opt for the stunning A685. I adore this road. It’s the perfect ‘trans-pennine link’ road. It has just about everything for a perfect A road for me. Pleasant scenery, long straights, sweeping bends, hills, places of interest (i.e - Kirkby Stephen, Brough) and most importantly, more than two thirds of it is NSL. The A685 and I go back a long way...

I really hope it’s not going to be ruined with needless lower limits, but I know it’s turn will come one day and then it’ll be ruined...
There are plenty of specific sections of classified roads I also enjoy using when I get the opportunity to, but that’s for another day and another poll.