I struggled to keep my humidity from dropping to 30% every day, with humidity in my house being at 50-55%, and 95% of the screen top being covered with foil.
Cypress mulch was great for humidity, bit of course was more expensive.
I gave coco husk bricks a try. $3 with a $25 order on Amazon. More work involved in getting it ready to be used.
I have recently been giving bath towels a try. I was warned of things like smell in a warm and humid environment. I can change the towel frequently. I foster kittens, so "ick" from the s ake is no big deal when compared to 3-5 kittens with diarrhea.
I say pick what you think you might like and try it out for a month. Each house/setup are going to be different, plus personal preference. Just stay away from pine amd cedar.