Composites are exactly what they sound like, a composition of several different materials, resins, epoxy, and wood fiber. This is one of the low maintenance options and will outlast your lifetime with no more than a little cleaning now and again. Most of the composite options will have a wood grain look. This material is heavier than wood and may require additional structural support. It can also absorb a lot of heat which may eliminate bare feet as an option when enjoying your outdoor living space.
Cellular PVC is similar to composite decking in the way that it is an engineered product. The biggest advantage over composite is that it stays cooler and is splinter free (think bare feet on a dark deck). It is 100% recyclable (but will last your lifetime so you probably don't need to think about that. It is lighter weight than composite, it dissipates heat better and stays cooler. Also, it tends to be more scratch resistant and will have better color fade resistance than composite.
Pressure treated timber decking is going to be the least expensive option up front. Other benefits include its natural look and lighter weight. Cons are possible splinters, the need for regular maintenance such as resealing the wood, and fasteners are more likely to back out and need tightening.