Depends on your plan. I only consider lifespan cost. Copper wins, works fine on lumber sheathing. I don't favor plywood. Last summer removed old crappy Onduline roofing and installed copper and some translucent panels that I recycled.
Had used more of the translucent panels on a tractor shed last year. A large oak came down on it last summer. Insurance co. is paying me handsomely to add the necessary 20' oak rafters, sheath with solid planks, and install copper standing seam. I milled the new rafters from the butt log of the tree.