My number 1 choice is Ipe, Mangarias, or Red Balau. In that order and pricing too.
Milk jug material or Trex, all have different grades. The original Trex had issues but later ones are much better. There are new companies out there that are making them look so much like lumber if you are looking from 4 feet away. Then there's the no name imports imports. I wouldn't put those thing in my worst enemy's home. its a waste of time and money. Personally, I dislike Trex. I don't use or build too many decks with milk jug deckings so I can't really suggest anything. This is just by talking with my suppliers and they give me tips on this stuff.
We just finished a deck for my neighbor a few housed away. Its a Mangarias deck with huge timber as support down below. We over built it for a none flex deck. Its up pretty high.
No, that ain't me. I am much uglier then that.