I'm also interested in this question.

Here's two things I saw on Jeff Morrison's (Flow author) Twitter:

* http://djcordhose.github.io/flow-vs-typescript/2016_hhjs.htm...

* https://gist.github.com/jeffmo/ef9214ca3acfe76c54a237b5710d3...

I found it easier to get started with Flow, but I eventually moved to TypeScript because it just has more mindshare, and isn't worse by any measure I care about.

I found it much easier to find tutorials, typings, and so on, for TypeScript. Editor support also seems to be a bit better (especially with VSCode), although the Flow-centered Nucleus plugin for Atom is pretty nice.