Posted By:
DavidAs the premise started with your favorite player, my all time favorite player is Robin Yount, so that would mean the card would be his 75 Topps Rookie.
My favorite Pre-War player is Christy Mathewson, and I'd pick his 1912 Boston Garter, though I'm not certain it exists (Leon, be kind enough to check your shoe box).
Honorable mentions Ty Cobb T206 Portrait Green Background.