Cypress is also dust free. ReptiChips is pretty much dust free too.

My advice is order a bag of it and try it yourself. You are going to get all kinds of different answers as everyones set ups are going to be different.

But i can tell you in 20+ years of keeping snakes, aspen has still been the best standby substrate for me. Yes, it is kind of dusty but you know what, i have never had an issue with the dust on any of my snakes. It is cheap and readily available which means you can throw it out every month or even every 2 weeks if you feel you need an ultra clean cage. You can mist it which will kill the dust and it wont mold unless it has been sitting soiled for a long time and wet. I personally would never let any substrate sit for over 3 months on a snake. You might not see poop or piss but you cant tell me the snake has not crawled across it at some point if it took a poop or piss in the middle of the night. Those particles of waste WILL get tracked around the cage even if you cant see it. Heck i think most of the substrates even tell you to change it out every 3 months at the longest.

Anyways, just order a bag and try it. just be aware that it is the least economical substrate so if you have lots of snakes, you will go broke using it unless you let the stuff sit in the cages for months on end which imo is kind of gross