I have replaced carpet 3 times. I settled on leveled & polished concrete and ceramic tile. I would not recommend anything else because there are always at least 2 rains per year that will flood DC basements everywhere. All it takes is a storm drain backup on your street. It makes sense to isolate everything important from the floor and to use a durable/solid floor finish. If you use an oriental rug etc. it can always be cleaned, but wood and carpet are generally no-nos for basement apts.