ReptiBark - my favorite. Good for humidity, have not had a problem with mold. I wash and bake it so I can reuse.

Aspen - use this on my sand boas. I would use it with my BP but I can't get my humidity right with it.

Newsprint / Butcher paper - ugh. Not a fan. They fold it over, spill water on it, climb under it. I don't like the idea if they use the bathroom on it over night, me not catching it before work and them having to deal with it all day.

I'll add newsprint would be best for new animals or sick animals so you can keep a better eye on waste and look for mites.

I have been reading and reading over the past few months on this subject. I think it really comes down to ways best for you.