I would view this mostly as a trade off of asthetics versus maintenance
and durability. Properly maintained natural wood will always look
better. The Trex type material doesn't look as good, but doesn't
require maintenance and will last a lot longer. It has been used here
at the NJ shore boardwalks in spots for a decade and has held up very
well in that tough environment. Cost is also a factor, but that can
vary widely too depending on what kind of wood you happen to like, and
of course how long you expect it to last.