With improvements to plastics and composites and better water sealers for wood, there's no right or wrong decking choice.
Deck contractors recommend you consider a style to match your house. Wood or wood-like composites might best fit older homes, while plastic or vinyl could be the perfect choice for contemporary residences. A breakdown of the different options:
Wood
This category includes the old standby, pressure-treated pine, as well as cedar, redwoods and tropical hardwoods such as mahogany or South American Ipe. Pine is the least expensive, but also the least attractive. Significantly more expensive are cedar and redwood, which have natural resistance to pests. However, left untreated, they will weather to a gray color. Tropical woods are at the upper end of the price bracket but exceptionally durable and prized for their beauty. They need no treatment, are naturally resistant to insects and fire and have a long life span. However, there are concerns that harvesting the woods comes at the expense of rainforests.
Composites
Each manufacturer has a unique recipe, but here's what they all have in common: a wood or organic product such as sawdust, wood flour or rice hulls combined with some type of plastic to form pieces of lumber. Some brands, such as Trex, use recycled wood products and plastics made of recycled milk jugs and soda bottles. Others, such as Timbertech, use only virgin plastics. Most composite products are made in an extrusion process, similar to making a hot dog, where the lumber mixture is pumped into a form. EverGrain, on the other hand, uses a compression process, much like a waffle iron, where the mixture is squeezed into a mold. Composites tend to retain heat more than wood but also are splinter-free, resistant to insects and moisture and, with proper care, won't split or crack.
Plastics
Plastics are generally more expensive than composites or cedar. Some brands rely on recycled products and others, such as eon, use only virgin materials. Exceptionally durable and as maintenance-free a product as you can find, they are impervious to insects and moisture, have a high fire rating and retain color better than composites. As plastics tend to swell and contract with temperature fluctuations, however, railings and boards can feel loose. Some complain that walking on a plastic deck can even have a bouncy feel. Though grain patterns and colors are improving, pure plastic still can't match the natural look of composites.