Pretty much every trophy from 1997-2010 has solid demand. The issue for new members understanding the trophy market is most sales are private. I know a couple E4 members submitting some solid options in the next pwcc auction. It will be interesting to see what they earn publicly.
Overall Rarity is the final frontier. It’s the natural progression. Once you achieve your wotc goals, the promos/trophies are where you end. Which specific ones you prefer is personal.