Paddock boots and 1/2 chaps. I have a hard time finding tall boots that fit both my foot and my calf. This way, I find the perfect fitting boot, then the perfect fitting half-chap. I also like that I drive to the barn in my comfy boots, just put on the chaps and good to go. Take them off afterward to drive comfortably, on my way home I can stop by the store to pick something up and still be comfy and not look too weird.
I agree that well-fitting tall boots give more ankle-stability while riding and can help your position. I've found that some 1/2 chaps are very soft and wishy-washy, while some have a tighter fit with stiffer leather and do provide quite a bit of support.