What comic book was the most popular in 1920?

Comic books were not even invented in 1920. They were first invented in 1934, with "Famous Funnies Series 1 #1". But in the 30's and 40's the comic book series "Action Comics" were the most popular. If you are asking for just 1 comic, then I think either Detective Comics #27, #38 or #40 OR Action Comics #1, #7 or #23.