For new projects, a lot of it has to do with what existing libraries and tools you can use to get to market quickly. For established projects, it's going to be

For new projects, a lot of it has to do with what existing libraries and tools you can use to get to market quickly. For established projects, it's going to be a hard sell to switch over. I really like OCaml for example but for web projects it's not practical. TypeScript is a decent compromise at the moment. I like that the industry is (veryyy) gradually moving towards strong typing though.