I actually preferred SML/NJ when I played with writing it, but OCaml "won" in the popularity contest. Some of the things that made OCaml "better" (objects, etc.) haven't aged well, either.
Still with OCaml finally supporting multicore and still getting active interest, I often ponder going back and starting a project in it someday. I really like what I see with MirageOS.
These days I just work in Rust and it's Ok.