I think the only substrate everyone agrees on is paper towel.
However, I use peat b/c I hate when paper towel gets wet, snakes poo and then smear it all over, getting themselves covered in it. Even for just a few hours, some weird skin infection can set in. No thanks! I'll take my peat moss any time of day. That bacteria that was mentioned. Asperguillis (spelling?) is found in the air anyhow. We inhale it all the time.