we started with Flow and moved to TypeScript a few years ago; converted 100k lines of code primarily with sed via regular expression find/replace; even then Typ

we started with Flow and moved to TypeScript a few years ago; converted 100k lines of code primarily with sed via regular expression find/replace; even then TypeScript was better but 80% of the better part was the library of available typings--Flow's support for lodash types was awful in comparison and we used lodash and lodash/fp all over the place