According to ABUGames, which isnt the pricing authority on Magic but does at least have a reasonable set of listings for oversized cards, the foil oversized Gisela, Blade of Goldnight is the most valuable (around $250)
Maindeck artifact removal is much more common these days, but just a few years ago, Ensnaring Bridge was a lock in prison/stax decks, at least in game 1
But since the overall power level of the game was so much lower then, a single turn rarely affected the game state as much as it would now
Here is roughly what each rating means: 1 = Garbage - These cards are unplayable in nearly all circumstances
Estimated value: $600 - $850 Take a look at these honorable mentions
14, you can get the Magic: The Gathering March of the Machine Draft Booster Box for $136.83, down from $149.99, at Amazon