The answer is......"cards of mostly unrecognizable figures in the major leagues as card companies continuously to inundate us with a checklist of prospects to cash in on the next big thing." Xth Round Draft Picks and Top 100 prospects are all the rage and have been for some time in this hobby. As one of many different kinds of collectors, I can tell you one thing, it is always tantalizing to invest in the upside of the little known and well regarded rather than the well known with varying degrees of being regarded
I was an avid Bowman collector for years because there's nothing more satisfying than discovering a player and making him a part of your collection for the most inane and irrational of reasons, you pulled the first card of that player out of a pack. Usually though, there were other explanations, that gave you the need to collect a player and seek out their cards, maybe something normal like team association or something visceral like photo selection or something greedy like value in the monthly Beckett's of old.
Let's see where these cards rank on the scale of collectability; all cards scanned are from a 2013 Bowman retail pack, the peak of buying a set for one player, Yasiel Puig (spoiler: none were Yasiel Puig).