If you want a good clean up crew I would recommend dwarf whites and springtails. They both reproduce extremely quickly, can tolerate extreme conditions, and help clean up. I would try to avoid drier species like zebra isopods, slower reproducing species like Cubaris sp. (though I don't think you'd get those for a ball python), or species that could harm your snake like dairy cows. For display isopods powder (blue and orange) isopods are cool but you can't usually have those and the dwarf whites as the dwarf whites will outcompete most other species.