There is a lot of debate on this topic and it turns out that a lot of different things work here. However I preffer a more natural setting for my snakes and for me newspaper or paper towels is just ridiculous. So far I've been using Nature Bark which is ok I guess, but for one thing it is not very easy to scoop and clean . So I'm thinking aspen shavings . I've heard of mold issues associated with it but I think it will be ok in my case since I have a very large water bowl to provide for humidity and I don't really need to mist the substrate with water . Mites were a big issue with my last snake I got, because the guy kept it on Reptibark. So with that being said I'm looking forward to hear your experience on this topic and please no newspaper or something that carries mites