Discuss HN: On the "Best" Language

I think it's time we have a discussion about the "best" languages.

Any seasoned/senior developer knows that there are real differences between languages, and that a measured approach to choice of language to develop and deploy a specific application is the best approach.

However, lately I have seen suggestions that any language is the "best" language so long as you love that language. This is false and will lead many junior developers to unnecessary headache and technical debt in the future.

Let's take, for example, speed. If speed is a factor, the lower level the language, the more optimized the application can become. If you need concurrency at a higher level, Go or Erlang would be the answer. Fast prototyping, node or ruby.

There are in fact differences in the application and efficiency of languages, and its best we don't ignore this.

There is no best language, only a best language at _________.

What are HN's thoughts on this? What languages are the best for what purposes? Would love to hear about some of the mistakes and improvements learned through experience that I know many on HN have to share, and I think openly sharing these experiences will really help strengthen the developers of tomorrow!