According to a report from DFC Intelligence, Dota 2 surpassed League of Legends in the first quarter of 2013 as the most-played "core" PC game in the West.
via N4G: pc news feed http://n4g.com/news/1230544/dfc-says-dota-2-passes-lol-in-the-west-riot-games-rebutted
via N4G: pc news feed http://n4g.com/news/1230544/dfc-says-dota-2-passes-lol-in-the-west-riot-games-rebutted