Though IntelliJ has amazing features for Java/Kotlin: it comes with a free version that packs most of 'm. I think saying it's all to sell licenses is a disingenious, lots of longstanding Java pain points get addressed by Kotlin in a really nice way. It has a really strong webdev ecosys building up, and comes with a rather interesting feature set as language itself. I'd say its good "typed Ruby" (OO at the core, FP where it makes sense, very expressive, dont type too much).
Scala's issues on the other hand stem, I think, from it being multi-paradigm. Where Kotlin is OO-core with FP where it makes sense, Scala is both OO and FP at the same time which makes it messy.
Frege explored being full FP on the JVM, but looking at the repo[0] it did not get much traction.
