Since merlin supports LSP protocol, completions, jump-to-definitions and other such stuff should just work in the majority of editors. REPL integration could be a little bit trickier, tho. There should be a mode for editor supporting utop.
There is reasonml plugins for both Idea and VS Code, which provide a good support out-of-the box. However, neither supports repl yet AFAIK. Emacs have a good utop and merlin integration, if you want to give it a try, both Doom-emacs and spacemacs have a preconfigured OCaml support.
@zeroexcuses I published a video this week to explain how to import an ocaml project with latest plugin version. You can find it here: https://www.youtube.com/watch?v=V8r5ys-6QUI
I hope you can find it useful.
It’ll give you completion/documentation out of the box for ocaml stdlib. And it works on any OS (hint: Windows)
Idea plugin is more focused on ReasonML because that’s my main usage now, but I’m slowly integrating more OCaml related functionalities. But far from “ideal”