A deck gives you access to the beauty of your yard and provides a great space for entertaining. It can also serve as a charming summer dining area or can be a great place to just relax.
Wood (Least expensive initially, but will require maintenance=$)
Vinyl (Very popular, maintenance free, less expensive than composite)
Composite (Closely matches the appearance of wood without the maintenance)
In the long run, it will cost less because it will be done right the first time.