Barefoot.
For me personally, I don't wear shoes, so I am barefoot 99% of the time anyway. So my feet are hardened from that, and rocks and dirt and broken glass don't bother me much. But, at the same time, I'm used to feeling whatever surface I'm on with my bare feet.
As a couple folks said earlier, historically barefoot would have been more likely for a slave on their way to be crucified anyway, so I would be used to whatever surface I was walking to my death (which might depend on the size and importance of the place I lived). But in this instance, on my way to the place of execution, I try to concentrate on the surface of the road, a feeling that I have felt countless times. I can feel the stones of the well-worn street and try to avoid the bits of debris, which is hard with the heavy patibulum on my shoulders. But the road distracts from my nakedness and the growing crowd. The road continues outside of town. But as I am pushed to the side, the feeling under my feet changes to dirt and grass, as I know we are close to my cross and I am taking the last steps I will ever take.