Commander is the most popular format for a reason
The loose math Im using is half plus one, under the logic that seeing more than half your deck is an unlikely event in most games and drawing significantly more than half your learn cards in a game is even more unlikely
Of which, there are a few honourable mentions: A Japanese promotional card from the XY era, this one can be found for around $8,600 when its graded to a PSA 10, although its average price sits around $7,500
As with most Reanimator decks, you've got a blend of cards that load the graveyard like Overlord of the Balemurk, Oblivious Bookworm, and even TLA's Gran Gran
Early Access to New Sets The Japanese market frequently gets new sets and expansions months before they are released worldwide
Its easy to turn it into a combo pieceit wins on turn 1 with Underworld Breach and Brain Freeze, generates infinite mana with Auriok Salvagers, and so on