As for ‘most popular’ by sales of recordings, Michael Ventura in Hear That Long Snake Moan mentions an early recording by the ‘Dixieland Jass[sic] Band’ which may have been the most popular recording ever, based on numbers sold versus size of population with players. He mentions sales of millions, in the early 1920s, and states that ‘nearly everyone with a Victrola must have bought one’. But of course the absolute number of sales of that recording would have been long superseded.