Natural look of wood
If the natural look of wood is a priority, use cedar. The heartwood of the tree (the deeper colored red part, not the white sap part) is rot resistant.
Cedar doesn’t readily absorb moisture – and, since moisture is what creates twisting and splitting, cedar decking tends to lie flat and straight. Western Red Cedar decking has unique, natural performance characteristics and exceptional beauty that bring warmth, character, and longevity to deck projects.