While wooden decks are the traditional choice, composite ones have gained popularity recently, as they are easier to look after. This is because they are made from a blend of wood fibers and plastic (often recycled) that won't degrade as quickly over time.
They don't require sealing or sanding. And, composite tends to be less slippery underfoot in wet conditions, too. If you're worried about the appearance, there's no need: many are designed to look just like real timber. The most common drawback is the cost of these decks, as they tend to be more expensive.