There is nothing wrong about PHP or JS, but I would like to learn a new programming language primarily focused on the backend. The problem is that I am not entirely sure which language to pick. That's why I am asking you for advice.
The language I would like to learn should mostly be used to craft backends for all sorts of websites and services: from "simple websites" with contact forms and so on, up to large SaaS products with a broad range of capabilities. It should be easy to start with but powerful enough to handle critical workloads. Ideally, it has mature frameworks which provide a solid base for things like user auth, ORM and database handling.
Also,it should be future proof, meaning no declining but raising usage.
The languages which seem most appropriate are
The following list contains some assumptions about the languages. I hope that some could verify or correct them if wrong. :)
Python is one of the most popular languages and is known as a universal language for programming in all sorts of fields, and became quite popular in the AI sector. It has popular frameworks for the web environment. A large con is that it's dynamically typed.
Ruby is used by many top web services such as Github or Stripe. From what I heard a lot of people swear on Ruby. I already worked with Rails a bit and it really is a great tool.
On the other hand I read some comments that it's kind of a dying language because it never had a large market share and now others take over.
Go is kind of the newcomer on the block. I heard a lot of good things about it because it was created to be used for the web, has a strict type system and should be easier to learn. Con seems to be the rather small usege at the moment. I did not find many job offers for it.
Last but not least, Java, or the more modern Kotlin. Java always was an "enterprise language" for me and feels rather slow and bulky, although it's used in many high-class systems.
I am not sure about Kotlin. It looks modern and like a nice evolution of Java, but I did not find many job postings for it.
What do you think about all these modern languages? Which one should one pick if starting fresh into the web programming business and what would be the most important selling point?
Or do you have other suggestions in mind?