I raised my chicks up on pelletized horse stall bedding. That stuff lasted FOREVER- if you kept it dry. Chicken poop? Not a problem. Leaky shower faucet? Moldy stinky concrete mess. In the (dry) coop it was very efficient, there was no smell, and even when the pellets had all turned into sawdust, the bedding continued to be usable... I often encouraged this by pouring hot water on the pellets when I replaced the bedding because it dried quickly and sawdust went farther. None of my chickens ever ate it. (although one of my neighbors fervently told me that my chickens would all get compacted crop and die horrible deaths if I didn't switch bedding right 
now- they were 19 weeks old and had not ever eaten it, except for a nibble when they were 2 days old) The biggest thing about it was the dust. Every time a chicken flapped it's wings, or jumped off the feeder, or took a dust bath, dust swirled up into the air to choke me. And although the birds didn't mind, I have some mild asthma and couldn't stand it.
  I finally broke down and switched to shavings, knowing they would take longer to compost and wouldn't last as long... but I love them! They last a little less than a month, just  as long as the other stuff (for me), when all my birds have four square feet of indoor space plus a poop board, and an unfinished run. (they do free range every morning, though) They are not half so dusty as the horse bedding, look much more comfortable, and don’t pack down as easily. I stir the shavings with my boots when I visit with my girls, so the poop gets mixed in and I don’t have a clean layer under the soiled layer, and the clean stuff isn’t wasted when I clean coop. Not that they don’t scratch around in the shavings looking for tasty things (like, I dunno, smaller shavings? They don't find anything, but they still look). The shavings don't get kicked into things as easily, either, although I'm sure they would fill up my waterer if I didn't use a nipple waterer. I also use it in the nesting boxes, and it works well there as well. They are very absorbent.
  I could not imagine using leaves for the whole coop- I used it for the poop board until my local 
TSC got more sweet PDZ, and the leaves had to be changed frequently, smelled anyway, and did not absorb any moisture, even chopped up.
   Some people use sand, and my sand/sweet PDZ poop board is awesome, so I could see how it might be nice for the whole coop. Some people use shredded newspaper, or straw/hay (a controversial topic), or the deep litter method, which I would like to try but my coop isn't built for it.