I've looked into both some time ago, and while both are great languages the tools around ocaml are atrocious.

Yeah, it's really unfortunate. Dune and Esy are moving things forward, but you sorta have to know the ecosystem quite well to figure that out.

Do you have a reference to the up-to-date guide that you'd recommend to get started in the OCaml ecosystem? The one that would cover editor integration (VIM/Emacs), build system, standard and essential libraries to use, etc.

I'm not aware of any, sorry. You can look at the dark repo to see how we do it though: https://github.com/darklang/dark