My favorit at the moment is Node.JS, because I really love JavaScript and it makes working with big/many I/O operations a blast and it it very scalable (need more performance? Just spawn more works or buy a bigger server)
However, depending on what I am building, Rust or Go might be valid alternatives. I wouldn't go for C++ any more and if you don't use ASPX, I do not really see C# as a candidate (I hate .NET, but that's a different story :) ).
Java... is an industry standard. It is OK and you will encounter it when working for some company, but personally, I wouldn't use it as I think it tries to mix too many responsibilities into one language (Jack of many trades, master of none).
I migrated away from PHP for similar reasons as you are thinking about using a different language.
As for Ruby and Python: I never really used them, but I read some articles from awesome developers who leave Python for Rust.
[Rust] supplanted Python for various things that I do.