Stones are the best choice for my location zone 6a on the side of a mountain, rain run off has us with a french drain as well as stones around the outside for help with drainage. I also appreciate being able to look at my coop and instantly know that there is not a critter hiding or digging. If i ever do get water in the coop I will throw at least 5 inches of straw on top so the hens are never standing in or drinking the standing water. When its sunny, I rake it all out and use elsewhere. I have used pallets, paver stones, logs, you name it. I have to say the french drain as well as some other small modifications to redirect the water. non issue now. gotta figure out what works for you and keep doing it. If it sucks, find a new way. I think one of the many joys of a backyard flock is the managing of this little world. Always adjusting this, modifiying that, watching for this, preparing for that, noticing the seasons and shifting lanes. Good Luck