Nielsen, a TV rating company, has done research regarding eSports and found some very interesting statistics. CS: GO is the most followed eSport in the world, with League of Legends right behind.
Call of Duty is at the top of those charts as well, being the most followed cross-platform game in US, UK and France. It is interesting to see FIFA topping those charts in Germany and not the UK.
Nielsen has also done a gender breakdown and here are some interesting facts.
As seen above, Overwatch fans are the most active during the week with 12.2 hours of playtime on average.
Important note: People who watch eSports once a quarter are also considered eSprosts fans in this study.