1958 Topps #418, WS Batting Foes Mantle-Aaron ⭐
IMO, this card is in the discussion for greatest two-player baseball card of all time.
The image itself is priceless - Two legends of the game, face to face, with USA red, white, and blue bunting adorned Yankee stadium as the backdrop.
There are many cards with a bigger price tag, but for my money this is one of the best.