I've used Carefresh, Back 2 Nature, shavings, Aubiose and shredded paper.
Carefresh and Back to Nature was too expensive.
Shavings too dusty, one of my boars has a reaction to it.
Aubiose stank even before use.
Shredded paper wasn't absorbant enough.
I now use fleece liners and wouldn't go back to any of the others.