Criteria can easily steer this list as there's just too many ways to define it, and too many 'rare' games that people oogle after.
I mean, Zaccaria guys are always trying to find Spooky.
Classic Stern guys look out for games like Cue, Viper, Dragonfist etc....
Gottlieb fans would give up an appendage for Krull, Goin Nuts, QBert's Quest
Lots of potential residents of this list for sure.