I prefer all dirt for coops on the ground, I use deep litter and only clean out about once a year. I would never spend the money to put down wood to have it covered in poop and rot. Also wood floors close to the ground are an invitation for rats to set up house keeping. I like my coops easy and carefree, so dirt floors and deep litter are what I go for. In addition deep litter provides many beneficial bugs and microbes that can keep your chickens healthier. The USDA even studied this and recommended it to commercial chicken people, not changing out the litter in the brooder houses between batches of chicks.
