probably stall dry wood pellets or pellet stove wood pellets, because you put them down on the floor of the run whole and as moisture gets on them the turn to sawdust and still keep a good absorbs rate. that is what I use on the floor of my coop and only have to change it out 2 times a year...
no reason the stall and wood pellet stuff are made the same. the stall stuff costs more and is harder to come by where you can get wood pellet stove fuel at almost any hardware store for cheaper.
I think this summer I will be adding a layer of sand to the run.I already built it up using large gravel 1 inch minus for drainage this has helped a ton for the run. inside the coop I use wood pellets as they work just as well as sand for poo removal but they absorb water moisture and also...
I have a small mini farm, I have 15 chickens is all and the flock is a mix of breeds. the chicken watch dog is a mini donkey by the name of casper he keeps the coyotes and racoons away from the chicken coop.
I use wood pellet fuel(one bag of wood pellets lasts all winter) it doesn't blow around the pellets stay put in the coop and as they absorb moisture they expand into saw dust which composts faster. they are easy to stir and virtually no dust.