All are good options. I have a hard time voting for a team card for top honors but that is just personal preference.
Another one that comes to my mind is the Rose Co. Archibald "Moonlight" Graham PC...
I know he wasn't the ballplayer that many on this list were but since watching the reading the book and watching the movie "Field of Dreams" I have wanted to own a Moonlight Graham card and this is his only individual item (he was previously known on team cabinets and team postcards.)