As a dev who works on both Java and C# code, modern Java (17+) and C# feel almost exactly the same (not sure if Java has extension methods though).

Bonus points for using Kotlin instead tho. I dislike both Java and C# just because they both allow any object to be null and that's usually a headache whenever a null exception shows up.

The only thing I like better about C# is the Fixture library for testing. I haven't found any mature libraries like it for Java yet.