[mpawelski]

Java is surely keeping up but I can't name single Java feature that I miss in C# or is implemented better in Java. I haven't used Java in a long time though, just occasionally I read about new Java features and I've never said to myself "cool, I wish I had it in C#".

Static import are also available in C# for quite some time now (c# 6, released in 2015, and in C# 10 you can even make this import global for for project).

I haven't used Kotlin, is there any killer feature compared to C#? (except more succinct code in certain cases?)

[tkubacki]

Kotlin is younger and made better choices by default, like immutable "val" as default option.

Also since it's Jetbrains - IDE integration is superior compared to anything C# can have (including Rider...)

[pjmlp]

Depending on how you look at it, better extension everything support on Kotlin's case, and a way to do DU, while it keeps being discussed for C#, people should just add F# to their codebase, but alas.