I started by learning what the company used; Java, PHP, Ruby, Bash, C. From there I picked up Javascript, Go, etc. Personally, I pick the thing I'm most profic

I started by learning what the company used; Java, PHP, Ruby, Bash, C. From there I picked up Javascript, Go, etc. Personally, I pick the thing I'm most proficient in and enjoy building with. In a certain context certain languages make sense. Dynamic scripting can be useful for rapid development. Javascript is usually a must for frontend or simplifies code sharing longer term. Backend you usually need something more performant so after much searching I finally found Go to be a perfect fit but again thats a personal preference. If working with a team I think it complicates things slightly. Now you must take everyone's skills and opinions into account. If working within a company you need to think about hiring and longevity of the code base. That's where normally you agree on 2-3 languages, again based on context and what's fit for purpose. If you're just building something for yourself, go with what you're proficient in. If you want to learn a new language, pick one and build something to learn the language. If you're working with a team, democracy usually wins. Hope that helps a little. Just my opinions and what I'm used to. Not gospel.