If the natural look of wood tops your list, use cedar for wood decking. Cedar doesn’t readily absorb moisture— and, since moisture is what creates twisting and splitting, cedar wood decking tends to lie flat and straight. The average lifespan of 15 to 20 years for cedar wood deck boards, but it can deteriorate faster when used for ground-level decks and for shaded decks that are slow to dry out, hence the reason we use pressure treated lumber for framing.
To retain the color, you have to clean it and reseal it every year or two, and even then it’s a losing battle. I’ve never seen 10-year-old cedar for a wood deck that still had that warm, rich look of new wood. Cedar is also soft; when used for stairs or for decks where furniture gets dragged around a lot, which will cause splinters.