Confused about what to choose, wood or Poly? There's no right or wrong answer but some insight may help. First, what is poly? Poly is actually a composite material consisting of a hard, rigid foam core wrapped in a PVC casing. The foam helps reduce weight and adds some stiffness to the product. An aluminum insert is used in some applications to add more stiffness. Poly comes in two forms, solid poly and hollow poly. Solid poly looks more like wood, however is significantly heavier than hollow poly. Hollow poly is lighter and more suited for larger shutters, but it requires inserts and caps that takeaway from its appearance.
When it comes to direct contact with water or very humid conditions, poly is the only choice. Make sure your shutter provider use stainless steel screws and hardware, not all manufactures do. Aside for those conditions, either product is suited for most applications. However, poly does have limitations due to its weight. Poly is about three times as heavy as wood and far less rigid. The weight, and the fact poly is less rigid, means the size of the shutters are limited. If the shutters are over 34" wide they may sag. For this reason wood is superior for larger shutters. Of course wood can be painted or stained giving you many more finishing options.