Here's a link for very old thread on same topic:
https://www.net54baseball.com/showth...t=top+ten+ruth
My personal list would be something like:
1. 1914 Baltimore News
2. 1916 M101-4/5 RC all variations extra premium for ad backs and rarer backs
3. 1917 any back Collins / Boston Store/ Biscuit...
4 (A). 1917-20 M101-6 Huge premium on Red Sox, then Yankees version 4B.
(The Red Sox version would tie as a top 3 really. )
5. 1921 E121-80 American Caramel pitching pose
6. 1920 Headin Home theatre cards (any, premium for nicer card stock/ better poses)
7. 1921 Frederick Foto , value and rarity wise merits a higher spot here but so unobtainable.
8. 1915 Red Sox Team PC
9. 1921-23 E220 National Caramel
10. 1932/33 US Caramel
11. 1933 Goudey all 4 poses, not rare but as classic as they come
12. 1923-24 White border Exhibits , exhibit rarity same pose as 1921
13. 1921 E253 Oxford Confectionery
14. 1925 Champions Exhibits
15. 1920 Carl Mays Tour postcards (ultra rare)
16. 1921 Proctor Theatre vaudville ad card (ultra rare)
17. 1926-29 Pose exhibits
18. 1922 W575-2 auto on shoulder
19. 1922 William Patterson
20. 1922 E122 (Rare, but grainer image than E121)
Honorable mentions no order(some of these would blow away some others above by value*): Star Player Candy, Uncle Jacks, Butter Cream, W503, all 1922 E121 poses, 1921 Exhibits, Other 20's exhibits and 1932 formal suit exhibits, E126, 1927/28 types york, yuengling/ harringtons, Pathe Freres Phonograph, Sport Kings, R315, Rare and attractive RPPC's, Big head strip Red Sox (ugly but early!) plenty of others as well.
My favorite RPPC shown here with Brother Matthias, Fred Merkle and wife (only copy I've seen)