What's everyone using for substrate these days?

[Bogertophis]

Newsprint sheets. It very safe, easy to clean up and affordable. I will never use anything else. I get my from Uline.

Terrible option, in my opinion. Not only is there no traction for snakes, but it's not that absorbent- everything that comes out of your snake just lays there on top for them to keep sliding through, whereas other substrates allow urates & fecal matter to sink in, with less contact for the occupant. Newsprint is cheap, but you get what you pay for- it's not the best for the animals.

I don't need to use humidity-retaining substrates for what I keep (though I do provide humid hides as needed). What I do is line the floor of most of my tanks with white paper towels (I like Bounty), then a layer of paper shreds (clean business papers shredded by me), then a light layer of Carefresh (very absorbent & also drying- ie. hygroscopic).

The paper towels offer traction & are very absorbent- they also allow me to roll it all up for disposal when I need to clean up.
The paper shreds allow heat to rise easily through them- I use UTH- and the shreds offer traction, security (for snakes that like to burrow, like my TX Longnose), & they absorb urates/fecal matter.
The Carefresh adds traction, absorbs moisture like crazy from urates/fecal matter, and also slightly weighs down the layer of paper shreds.

Some of my snakes (the largest ones) use indoor-outdoor carpet instead (the backless kind) cut to fit* their tank; it can be spot cleaned or hand-washed as needed (disinfected too) almost infinitely- it never seems to wear out, if you're "green-minded" & hate buying & disposing of tons of cage litter. It allows UTH heat to rise easily thru it (& is not flammable as paper is), offers traction, & after hand-washing, dries fast, OR it can be shaken out & reinstalled quickly while damp to add humidity. It comes in nice cage colors (green, brown, tan, gray) so it looks nice IMO. It absorbs much better than newsprint too but depending on the size you're using, you'll need to hand-wash it either in your bathtub, or in a laundry sink (which is what I use). It doesn't allow snakes to burrow unless they just go under it, so I wouldn't use it for snakes inclined to burrow (like kings & gopher/bull snakes). For the right kind of snakes, it will save you lots of money on substrate- just saying.

*What I like to do is cut the carpet (easily cut with good scissors, btw) so it's about 2-3" bigger than the cage floor on every side. Then I cut a square (2-3") out of each corner, so that when I install it in the tank, the sides easily fold up about 2-3", allowing the floor portion to remain flat, & all sides have a border that encloses wastes, & offers a bit of privacy too. You can find this kind of carpet sold in Home Depot or Lowes & other home improvement stores, often sold by the foot on huge 12' wide rolls. Do some figuring ahead of time- may I suggest using graph paper. It's not expensive, & practically pays for itself. Let me know if you ever manage to wear it out.