I need some advice to choose a language for back-end development. Right now, my REST APIs were created by using Flask/Django, and I'd like to create a more reliable and more efficient API with static typing. On the one hand, Go is young, very light, and syntax like Python's, but C# has a large number of libs and more built-in methods. Which is the best solution today?
I recommend Go for backend. It's younger than C# doesn't mean it's not mature. It's already mature enough to be run on production. You can see there are already many companies in the world adopting Go as their backend business logic or tooling. I can name a few like Github, Shopify, uber, twitch, and many more. It's easier learning curve, low entry barrier, better performance than C#, better memory consumption than C#, since there's no VM/runtime needed. It's suitable for large scale system and large codebase for readibility and long maintainability. It's simpler than C# since no class, inheritance(this can cause hard to maintain software), exception, etc. You can still implement OO way in Go without those feature. Simple file structure, only main files and package files. It compiles to single binary and easy to deploy and work around it, unlike C# who compiled to IL and you need to wrap all those IL files to be run inside separated web server(even .Net/.Net Core platform provide built-in web server). For libs, don't worry, there are many open source libs you will found on Github and already adopted by many companies. Go is employed in personal, startup, even corporate level.
From times to times I asked or was asked that same question. Technology aside, it's important to consider the skills and expertise that the dev team has. Whether you use language A,B or C or framework X,Y and Z, if your team has a strong background and experience with something make it count too.