[sethammons]

I think Go matches your criteria. I've put more eggs into my Go basket than my Python one. For myself, I focus on building networked distributed systems. Go helps me do that (and build useful cli tools). I mostly resort to Python for scripting.

What type of programming do you want to do? I don't think I would recommend Go for game development or embedded systems (though people do it).

[MTemer]

For personal reasons I have to stay a couple of years at my current job (back-end and some ops), I do some boring stuff but the payment is nice. I don't want my brain to slow down too much so I'm looking for a language to do random stuff without thinking much about what exactly I'm going to create. But probably something related to web development, cli tools/automation, maybe a desktop app just to put in my CV (Qt?).

[sethammons]

I've seen QT binding libs for Go, but I am not familiar with them. Go shines in the back end, but I think Python would likely be a better choice for a desktop app with far more examples to learn from.

More than becoming an expert in a given language or stack, another thing to consider is learning a domain. I'm partial to distributed systems, but if image or audio processing, or desktop app, or whatever it is what you find interesting, diving into those will keep you from getting stale and make you more marketable if and when you decide to move to a new employer. The tech stack will reveal itself or you will find that it is fungeable. The key for the resume there will be personal projects, meet up talks, and blog posts as opposed to work experience. At my work, we would be very interested in talking to such a person interested in distributed systems.

Whichever you pick, I hope you find fun.