We service a lot of horse barns! It never ceases to amaze me at the different styles of floors in stalls. Dirt floors with shavings or sawdust are generally the worst. A good % of those customers will tell you the horrors of having their horse stand on concrete or pavement, etc, but then you look at the stall and it is 2-3 ft lower than the barn aisle and shaped like a bowl. Or there are potholes all over the floor. they can expain the virtues of a dirt floor, but they can't ever get the maintence done to keep the floor level. These are my prefrences.
1. Concrete sloped 1" in 12' to back drain with 2-4 inches of bedding
2. Concrete with drain - rubber pad on top with bedding
3. pavement with 6" straw
4. wood floor on top of french drain bedded with sawdust/shavings
5. gravel covered with mats covered with sawdust/shavings
6. dirt covered with mats with sawdust/shavings
7. dirt with sawdust/shavings
One of the nice things about solid floors ie. concrete, they can be cleaned, powerwashed, and sanitized - very hard to completly clean dirt floor. And your horse is never standing in a bowl!