Reptichip has by far been the best I've tried. I've used paper towels and aspen previously and there is no comparison. The paper towels were consistently needing to be changed and the smell was horrendous plus humidity was always an issue. Aspen helped with the smell and humidity but was molding and still smelled. The reptichip does not mold, keeps humidity up and almost completely eliminates odor. It is a type of coconut husk I believe. All you need to do is spot clean and I do a full change every month or two. There is no smell, they are never laying in their piss and humidity is great. I will never go back, it's a little pricey but well worth it!