> Honestly Go seems to be over its honeymoon period and is probably a safe bet also
This. Go is an established technology by now. Plus, it is really, really easy to learn and get productive in...I mean, being accessible even to beginners was one of the design goals of the language. One can literally get to grips with its basics over a long weekend.
Yes. I was comfortable in Go in about a week. It lets you do most of the things you really need to do in a web backend without too much bother. The language is generally well behaved. There's no framework-of-the-week problem.
JavaScript/TypeScript/Node/React/etc is a treadmill.
There are some great web frameworks out there (gin, mux, echo, etc) but one of Go's strengths is that it's just as easy to stand up a server without them.
I've done some personal projects in Go (golang?) and I respect it as a modern development language.
Rust is on my TODO list to dabble in; at least at a glance the language has a solid conception, a clean syntax for portability, and the language syntax appears to lean towards clarifying much of the undefined behavior optimization other languages get humans into trouble over.
I'd even take mono / C# over Java; but that's just because of the real world enterprise nightmares I've seen... all the fossilized versions of vulnerable libraries everywhere.
I would go for C#, Java, or (if you have a masochistic streak) C++. And SQL.
Honestly Go seems to be over its honeymoon period and is probably a safe bet also (there's 500 Go vs 600 C# jobs on my regular UK job search site).