I personally picked Flow because it was (and still is probably?) a much sounder and stricter type system than TypeScript. However, keeping up with the constant

I personally picked Flow because it was (and still is probably?) a much sounder and stricter type system than TypeScript. However, keeping up with the constant breaking changes (I helped maintained a few complex flow typedefs) led to me getting disenchanted and burnt out with Flow. Also, at one point a change was introduced where most (or all) internal errors would just cause a type to decay into `any`s, which frustrated me a lot. I don't hold it against Flow though; its only customer is the internal React team, and it's a 0.x software too. We've migrated our code to TypeScript later and it was a bit smoother sailing (although the typedefs for a few popular react ecosystem libraries were just... Abysmally wrong, it didn't matter at the end of the day; it was still easier).