My favorite for both of my guys (ball python and blood python) is a blend of cypress mulch and eco earth. I use Forest Floor cypress mulch and the Eco Earth that comes in bricks. I get the Eco Earth in 3 brick bundles for about $9 or something like that. Anyway, it holds humidity pretty well. I normally use about 60% cypress mulch to 40% Eco Earth, and I love it. Its really soft, and my Blood is constantly burrowing in it.