They all have their uses, and this is a more complex question than "which substrate is best for herpetoculture".

My ball pythons and carpet pythons are currently on paper towels. I switch to cypress mulch in the winter to help boost humidity a little.

My blood python is always on cypress mulch.

My western hoggies love Care Fresh pet store bedding, essentially a paper product.

I use ABG mix in my planted terrariums/vivariums/paludariums.

I like long fiber sphagnum moss for my lay boxes.

I like coconut fiber for many uses, but don't currently use it.
I like aspen and sani as well, and find that it and Care Fresh serve the same purposes for me. A bag of Care Fresh lasts me longer, however.