Probably a spider-like robot, with 8 arms/legs would be the ideal. I could also see a dog-like robot with four legs which give twice the traction with a low cen

Probably a spider-like robot, with 8 arms/legs would be the ideal. I could also see a dog-like robot with four legs which give twice the traction with a low center of gravity as well. Or novel designs, like what we saw in the Interstellar movie.