Yeah, calling it the most popular requires defining popular in a rather unconventional manner... That said, as a data point, a handful of years ago I saw a repo

Yeah, calling it the most popular requires defining popular in a rather unconventional manner... That said, as a data point, a handful of years ago I saw a report that the average iOS user generally had a quite a bit more purchasing power than the average Android user, so despite making up quite a bit less than 50% of the mobile market, iOS users actually come closer to making up 50% of the market that most advertisers care about reaching. I don't know if this is outdated these days, with more high-end Android phones than in the early days, but it still fits my anecdotal experience of Android phones being given to children as their first phone, and cheap Android phones being very popular in developing countries.