This isn't helpful for you if you're trying to pick one, but I find OCaml and Scala somewhat complementary for my tastes:
Scala is a pretty great investment for services, big data, etc. It has a robust ecosystem.
However, the compiler is slow, and startup time can be slow (and Graal and Scala Native just aren't options yet), and if I want to make some tool that gets called fast in a loop or deploys as a "small", native binary, OCaml is nice alternative which I prefer to the only other compelling entry in this area, Go.
Scala is a pretty great investment for services, big data, etc. It has a robust ecosystem.
However, the compiler is slow, and startup time can be slow (and Graal and Scala Native just aren't options yet), and if I want to make some tool that gets called fast in a loop or deploys as a "small", native binary, OCaml is nice alternative which I prefer to the only other compelling entry in this area, Go.