On a practical level, I'm very fond of the strict evaluation and the lack of purity. Its easier to write "traditional" imperative algorithms when you don't need to use monads or monad transformers everywhere.

When it comes to resources, I don't think Haskell is strictly superior. opam, merlin, and utop are pretty nice... I'm also very fond of the menhir parser generator.

On a theoretical level, Ocaml does have some neat things missing from Haskell, like its module system (with functors), polymorphic variants, etc...

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BTW, I wouldn't dump Ocaml in the "object oriented" side of things together with Scala. Nowadays the OO infrastructure is more commonly used for polymorphic variants than for OO, to be honest.