C, because I care about speed, program size, and multiple CPU architectures.

Or Stackly, a language I've been writing for nearly two years now. Like C, it's performant, compiles to tiny binaries (it maps fairly close to assembly under the hood), but unlike C it has a ref-counting GC, compile-time and runtime type safety.

    set [hello] fn 'displayln [Hello, World!]
    hello

I did used to care a lot more about community adoption or libraries, but less so today. If you're not dealing with protocols or encryption, and there is no library, and you can spare a month or two, then writing the library isn't a hard task. First fortnight to implement, six weeks to fuzz n fix.

But then, I've been forced to work with all sorts of estoric languages in my work, from PL1 to FORTH to Brainfuck, so my experience is unlikely to be the norm.