I'm about to begin working on an API, for which I plan to add GraphQL connectivity for processing data. The data processed will mainly be audio files being downloaded/uploaded with some user messaging & authentication.
I don't mind the difficulty in any service since I've used C++ (for data structures & algorithms at least) and would also say I am patient and can learn fairly quickly. My main concerns would be their performance, libraries/community, and job marketability.
Why I'm stuck between these three...
Symfony: I've programmed in PHP for back-end in a previous internship and may do so again in a few months.
Go: It's newer than PHP, I've heard of its good performance, and it would be nice to learn a new (growing) language.
Go with Node.js. There's something really satisfying about being able to use a single language across your entire tech stack. Especially once you integrate GraphQL, which is effectively JSON.
Your second best option is Go, but the ecosystem around Node.js is quite a bit stronger. This will play a big factor when you start building functionality like file management, messaging (especially in real-time), and authentication. The libraries and documentation are just stronger for Node.