terrible list of 20 cards to choose from
http://www.ranker.com/list/best-baseball-cards-of-all-time-v2/sabrjay,
1933-34 Goudey Nap Lajoie
1909-1911 T206 Eddie Plank
1869 Peck & Snyder Cincinnati Red Stockings
1915-16 Sporting News Babe Ruth
1934 Goudey Lou Gehrig #37
1914 Baltimore News Babe Ruth
best player ever. Only 10 examples known to exist.
1952 Topps Mickey Mantle
1909 T206 Honus Wagner
1910 T210 Old Mill Joe Jackson
1915 Cracker Jack Joe Jackson