Kotlin's actually pretty big these days. Not just in Android but in general development. Seen a ton of jobs lately where they're looking for people to write stuff in Kotlin (and Scala) specifically because it can interface with their old Java stuff cleanly.
On the subject of Java generally - I don't think it's all that bad. It can be verbose at times but one of the advantages is that you rarely run into code you can't understand. Everything is laid out in almost excruciating detail. And in some ways that's nice - it's a very idiot-proof language that is nonetheless very powerful and performant.
And as far as I'm concerned, the JVM is God-tier. The fact that it reaches near native performance is very impressive.
C# is excellent and I'm glad to see it's getting more widespread adoption now that Microsoft started open-sourcing their reference implementations. The CLR is not nearly as robust as the JVM but it's still really good.
If there's one modern language I absolutely fucking hate, it's Javascript. Not the syntax or features, mind you, but the execution model. The single event loop, asynchronous, non-blocking etc bullshit is fantastic for graphical web applications but absolute ass for everything else. The fact that it seems to be used for everything except what it was originally designed for is a tragedy.
There's so much shit that should be simple and elegant that gets turned into a spaghetti of promise chains and nested callbacks when you do it in Javascript because the language isn't designed to do what these webcucks are trying to make it do.