Why do we use wood for decking instead of other, better, materials that will last longer and not be so prone to insect infestation and sun and water damage? We build almost everything with wood because we have been doing it for so long. The oldest construction profession was manipulating wood. So, we are used to it now. The feel, the look, we even refer to the grain of it like it adds value to the structure. We use special oils and varnishes to bring out that grain. However, wood is not resistant to the environment at all. When it was alive it was very resistant. Now it is essentially dead and the sun, the rain, insects, and wild animals can easily damage it. One of the common options is something called composite decking. Composite decking is made from pressurized recycled wood fibre and glue. This means that composite wood cannot splinter. It is also water-resistant. That means water will slick off it but not forever. Because it does contain real wood fibre it can be damaged by rain and rot but far less likely than wood. Wood is open to the elements composite is sealed.
Now composite decking needs to be made properly. Getting it cheap is likely to end badly as the decking was not made properly. Badly made composite decking can disintegrate over time and turn into mulch if the glue used to connect the wood fibres was not resistant enough to water and sun damage. This is important to consider. A real wood deck can be protected and veneered with UV resistant and water-resistant coating. The composite wood is manufactured and does not work well with coatings and varnishes as the surface is slick. The varnish will just bubble up like you are trying to paint over a pane of glass. If the manufacturer did not make it with a UV and water-resistant coating, then you will have wasted your money.
The high-quality composite maybe even more expensive than wood so that is also important to think about when budgeting your deck. This expensive modern composite is colourized with different wood patterns and is pressed with random textures to make the appearance of real wood without duplicated slats as you would get from linoleum. This means you can have the same quality and aesthetics of real wood without the upkeep and rapid ageing. This deck will certainly last longer but remember that is not permanent. It will eventually need to be replaced.
So, which do you choose? A composite deck can be cheap and problematic but so can wood. If you buy from a respected supplier and pay the full price for the wood, then it will be similar to getting high-quality composite. The only real difference anymore is that composite should last longer and should not need any type of upkeep through its like while wood needs to be retreated yearly with water-resistant and UV resistant coatings.