Trex and other plastic composites are HOT on the feet and really hot to sit around in the sun.

Think having a backyard BBQ on a hot summer day on your black shingled roof.

They also expand and contract more than any other decking product.

If installing in the cold, a gap of 1/8 to 1/4 inch at the butt joints is required( butt ugly), Otherwise when the sun hits it it will expand so much that it will actually break the screws. Yes, even the high dollar screws designed for trex.

It will look nice if you are a fan if [bleep] up butt joints, but using it and walking on it will not be an option unless the deck is out of direct sunlight.

Cedar is not as it used to be
The Old growth cedar from decades ago is all but gone. What we have today is lowland fast growth. Soft, not as resistant as old growth and will not only not old a finish it will not hold up over time.

Treated sucks. It is treated when the wood is wet(still green), after installing it shrinks so much your joints can look like Schit.
Plus it needs to sit for at least a year for it to air dry be for you can stain or seal it.

What’s left. Brown treated if it is treated after kiln drying. More money that plain treated but worth it. Or a composite that is very light in color with special hidden fasteners.

Give a man a fish and he eats for a day. Give a man a welfare check, a forty ounce malt liquor, a crack pipe, an Obama phone, free health insurance. and some Air Jordan's and he votes Democrat for a lifetime.