Not rarest, not most valuable, but the ones you enjoy the most? The cards I happen to enjoy looking at the most are [in no particular order]:
T218 Jack Johnson [side view]
T225 Jas. J. Jeffries
1955 Topps Hocus Focus Marciano [w/Walcott getting KTFO].
N28 John L. Sullivan
1920s Flying Fist Benny Leonard
1960s Israeli issued Cassius Clay
1890s Wood cabinet George Godfrey
1935 Brown & Bigelow Joe Louis
E282 Jack Dempsey
1950s Rocky Marciano PC
