To me, it depends on the circumstances. certainly, a spider can more readily crawl out of being in a pit more easily than a snake can. If I am going to be stuck down there "with them", then I prefer the spiders (they can get away, even if I can't). If I am going to be up here "looking at them" from a distance, I would prefer the snakes be down there. They might, with time and interest, make it out, but I doubt it.