Powder coat is much more durable. It takes a pretty good whack to chip it. Just make to tell your powder coater to not build it up too heavy on the bead area if the wheel. I've seen wheels, both powder coat and painted, that had too much material buildup on the bead seats, which prevented the tire from seating. Essentially the coating made the wheel a slightly larger diameter. Kind of like putting a 16" tire on a 16.5" rim. It'll go on, but it won't seat. Or at least not without exploding.
