I like coconut bark.
I get compressed blocks from the garden center that you soak to make come apart.
So far I haven't had any problems with mold etc. or feeding. My snakes really like it.
Ambient humidity is pretty low up here, usually 15-20%, so for me keeping the humidity up is hard to do. The coconut really soaks up the water and releases it slowly. Helps alot for shedding.