I think it is a combination of things. Personal preference, based on our experiences or the recommendations of certain people, can be pretty strong. Availability and cost plays a part for me. Then something a lot of people tend to forget, we are all unique. Our management techniques and climates vary tremendously. Our coops look totally different. Some of us have sandy soil that drains well, some have a clayey soil that holds water. Some runs are positioned where they drain really well, some are low and collect water. Some of us have high chicken densities so the poop builds up, some of us provide lots of room so the poop is more spread out. Some regularly scoop the poop so certain beddings work better with that technique. Some people turn their coop or run into a compost pile with the deep litter method, a lot of us do not. Some open air coops allow rain to blow in and get them pretty wet so they need to dry, other coops are bone dry. The differences go on and on. But what works well for one person isn't always so good for another.
I cut long grass from areas I don't mow or weed eat, dry that, and use it for nests. It's free for a little work but I need to hand remove it anyway. Others use straw, hay, wood shavings, wood chips, sand, Spanish moss, carpet, rags, feed bags, and who knows what else as nest material.
My main coop is the end of a long shed. It was reasonably high but rainwater could wash into it from the hill above, so I hauled in some clay dirt to raise the floor a bit more. it stays dry. I use wood shavings on top of that dirt. It stays so dry I only change it out every three or four years. I don't have to but I like to put that stuff in my garden in the fall. By planting time it has been composted in place. I use a droppings board and put the pure poop from that in my compost pile.
My run is on a slight rise so it stays fairly dry and drains reasonably well. But when the weather sets in wet it can be fairly muddy. I have some strategically placed pavers so I can get to the feeder and waterers out there without getting too muddy. I do not put a general bedding on it. The chickens have places they can get out of the mud so they do OK. Some people would be really upset with any mid so that's another factor. Our expectations of what we want out of the bedding comes into play.
My suggestion is to try something and see how it goes. If it doesn't work out try something else. Trial and error.
