I've been using Reason for a couple of years in personal projects and I really like its fast compiler, type system, things like variants, modules. I didn't have OCaml experience before but to me it feels like being able to program in a very mature programming language while still being able to target JS. The community is great as well. Also refactoring code has never been easier in my opinion. That's why I also decided to use it for Tella.

I've used TypeScript a lot in the past as well, and I'm not against it at all. You can do a lot of the things you can do with Reason in TypeScript. But I do have the feeling Reason makes me a lot faster than when I worked with TypeScript.