Not everyone needs Demonic Tutor in every deck, but Diabolic Tutor is a steep drop-off
Somewhat counterintuitively, being non-foil isn't necessarily a bad thing, especially for rare box toppers, which are actually more valuable in non-foil than in foil
Breaking the Rules For just a moment, lets ignore specific cards, deck archetypes, themes, and flavor and just consider how Magic: The Gathering actually functions as a game
The most valuable serialized card according to TCGplayer is the Cavern of Souls / Paths of the Dead from LTR at a staggering $3,975
The main difference between the two is that the end result of the vote matters for will of the council, while each individual vote matters for councils dilemma