From my personal experience, Flow prioritises soundness in its type system, and thus can catch some bugs that TS won’t, but the TS tooling and editor support is drastically better than Flow’s.
Edit: oh and it’s worth noting that I’ve had much more luck finding TS definitions for third party packages than I have with Flow.
Edit: oh and it’s worth noting that I’ve had much more luck finding TS definitions for third party packages than I have with Flow.