What's the better roof?

The thing to remember is no type of RV roof is maintenance free. EPDM and TPO require the most maintenance, special cleaners, and generally have the shortest life. Fiberglass comes in multiple types from thin Filon roll material, to stuff as thick as a boat hull, it too needs care, which includes repainting every 5-10 years (many people use boat deck paint). The final somewhat common type of roof is Aluminum roofs, again they can be thin roll type material, or thicker peaked roof material. Aluminum roofs are nearly maintenance free, but may need repainting in rare situations. All types of roofs need attention to their edge sealing, and caulking around roof penetrations (vents, antennas, etc.).