There's a few candidates.
The last move of the Gold Coins Game:
The bishop move heard around the world in the Game of the Century:
This utterly ridiculous move, so hard to find that even the engine doesn't consider it at all until you play it (and even then, it actually lags for a few seconds before the realization kicks in):
Or how about this queen sacrifice for the ages?
Oddly enough, Mikhail Tal doesn't seem to have a ton of moves that many people think of immediately when they hear "best move ever," despite his reputation for playing incredible moves that seem completely idiotic at first glance. I guess it's because Stockfish can be a real killjoy at times, showing how the opponent can save themselves if they play the exact right moves.
I'm fairly certain that Mikhail Tal might have played it.