For a wash floor that's going to get serious use I'd want concrete. I would recommend using a penetrating sealer as soon as it has cured long enough.
If you want a concrete wash floor to do double duty you're going to have to coat it with epoxy or rubber. After 25 years of heavy use our concrete floor was starting to get rough. Since every epoxied floor I've ever seen has to be chipped, sanded and recoated on a continuous basis, we coated ours with Rhinoliner. We're in year 7 with no issues other than area of poor prep work by the applicators.
PS: Which is why I can't recommend the Rhinoliner company for this purpose, since they say up front that everything is guaranteed, then say the local applicator is responsible for the guarantee, so go sue those guys.
Good product, but given the choice today I'd probably use Line-X.