Honestly if I had the chance to do it all over again, I would have preferred a dirt floor. I don't have any flooring issues until winter. When there's snow on the ground the girls refuse to go outside. And in NW Ohio, winter can be a long ordeal. All that wet poop piles up, and before I know it I've got a wet, stinky, horrible mess that is not pleasant to deal with in the dead of winter. If I had dirt floors, that moisture would drain in to the dirt floor.
As it is, I have a wood floor with a 3/8" conveyor belt covering it. I work at a conveyor belt factory so it's free for me. However, it is as slick as a greased pig on a butter slide if it gets wet. So of course I put pine shavings down on top of the belting. But still the aforementioned poo in the winter sits on it and never drains.
I recommend you think about the conditions you will be dealing with throughout the year before you decide on a floor. Once it's in, it's pretty permanent.