basically, on paper flow is better. However, lack of Windows support and poor tooling, plus the fact that it was second to market, slowed down its adoption. Now

basically, on paper flow is better. However, lack of Windows support and poor tooling, plus the fact that it was second to market, slowed down its adoption. Now you have the issue where TypeScript has thousands of type definition for a lot of libraries, and Flow only has a few. Facebook keeps underestimating Windows (eg: there was a survey out for a while asking people if they should just stop working on Windows support for Jest and depend on Windows 10's linux userland support instead). That, coupled with Flow being harder to get up and running, makes TypeScript much more popular for the average developers. I still prefer Flow though :(