I'm one of the weirdos who likes OCaml syntax, but in my eyes ReasonML is unfortunate. It fractures the community for (ironically) no real reason - not only is it a new syntax, they're now writing a new standard library for it (Belt), as though the three existing ones (plus the JS one!) weren't enough! I don't think the new syntax is particularly nice either.

I don't think js_of_ocaml supports any kind of JSX. That's the only real reason to use Reason over OCaml that I know of, and it's a good one. But if I'm being frank, even if OCaml/Reason is a nicer language overall, TypeScript is a statically-typed frontend development story that has way more community buy-in and way fewer rough edges in the ecosystem. Just use it.