While it's not an ML-style language, I've found that I enjoy Clojure the most when it comes to JVM alternatives. The lack of F#-style pattern matching makes a few things feel less elegant, but the general structure of my code is extremely similar.
There is core.match[1], and between the restructuring bind, multimethods, and the ability to create polymorphic functions like hello in this example[2], you can replicate a lot of common FP idioms reasonably well. It's not pretty, but Clojure generally isn't.
