Hello everyone!
As a general rule of thumb, prices on cards, like all collectibles, are based on supply and demand. There needs to be a sufficient amount of demand that is significantly greater than the supply of these cards in order for prices to increase. There is also a consumption factor, the willingness of an individual to spend on these collectible sheets of paper. With this concept in mind, what drives demand for these cards? What is it that makes two equally rare cards from the same set, greatly differ in prices? **Keep in mind that the short run of increased demand on certain cards from deck-building are removed from this consideration - these cards will have been completely rotated out in this scenario.
A simple case study that many can relate to:
ex Delta Species - Kyogre*, Groudon*, and Metagross* were all worth at around $15 (at most $20) during the first year they came out. Kyogre* was the more fortunate of the three, occasionally reaching $25. Now, ~ 7 years later, you cannot find a mint one that is less than $45! In addition, recent sales indicate that Groudon* is "more valuable" than the Kyogre* now! Why is this the case?
As for my thoughts about what cards will be more valuable from these new sets:
I agree with the previously mentioned comments about Full Arts. I am not entirely sure how these cards would play out during the long run since there really has not been an analogous card from older sets to provide a comparison; however, I am very surprised that Secret Rares from the B&W/Plasma era, specifically SR Charizard, have not been mentioned at all! The trends from the past series of sets, specifically the sets containing gold stars, have indicated that these cards will increase in value! Even certain Legend pieces from the HGSS series have started to increase price a little!
A perspective potentially worth considering.
Best,
cpbog1
