Say, i want to build tcp client for check connection and can deploy anywhere without install any dependency, so i think golang would be a great choice. Maybe because your team are more comfortable with Python or dealing with AI/ML stuff, Java if you're dealing with Android apps, or because you are working on bank company, Rust for efficiency or some web server, Elixir i heard it's good for building messaging apps, C# for games, and even visual basic if you're dealing with legacy stuff.

No matter what people say, the reality is that people use languages they know best. And unless you strive for the best possible performance, there is really no other reason to change that. Do not let perfectionism be in the way of "good enough".

Also, you can ship fast and write more performant version, possibly in different language, later.

1. What’s vaguely appropriate. You’re probably not going to write C++ for browser frontend, and JavaScript is probably not a great choice for embedded. But there are a zillion equally valid options for web backends, for instance.

2. Ecosystem. I might choose a language for a game based on available frameworks. Or Python for ML based on available libraries. Or if you want to work with XMPP, Erlang is handy to know.

3. Familiarity. You’ll move faster and write better code with a language and ecosystem you and your team are already familiar with.

But often there are many valid options and you just have to choose one.