I use PHP when working on any website which does not need RTC and does not have ten thousands of visitors per day. That's why all websites I create for money as a sideline use PHP. PHP is available anywhere. It is reliable, easy to use and allows for fast prototyping.
However, I also really love new toys, like WebRTC and WebSockets. So when working on certain hobby projects or products for my company, I use those techniques to speed up communication and allow for amazing new features. That's when I use Node.JS.
If performance matters and your algorithms can be written highly concurrent, Go might be a good alternative. Other than that, Java is an industrial standard, though when it comes to number crunching, I'd go for Rust.