Each material has its own advantages and disadvantages. Composite materials (like carbon fiber or fiberglass) are nearly universally “better” for SUP paddles than aluminum. They are lighter, more durable, and can be tuned to offer exact performance characteristics. Carbon Fiber is not inherently better than Fiberglass. Which versions of those materials, how they are made, and how they are put together make a big difference. One of the highest-rated racing paddles among professional SUP athletes uses a shaft that is actually made with a blend of carbon fiber, fiberglass, and aluminum!