EPDM is a rubber material and TPO is thermoplastic. I would chose the TPO over the EPDM, it is a more durable material and will resist punctures and tearing from tree branches better than the EPDM. Having said that my EPDM roof is 25 years old and still does not leak. The white surface will slough off with time and the elements and eventually you will see the black sub coat. Coating the roof with Henry's, Heng's, Buscoat etc will preserve the EPDM longer and the white coating will keep the camper cooler.