I have a lot of JavaScript history, but if I were optimizing for the things you want to optimize for, I would absolutely pick Kotlin above JS+TypeScript. It's got bunches of language features, including superior concurrency, and runs on a faster runtime to boot. Unlike TypeScript, it doesn't have a 20+ year old dynamic language at its heart.

In backend systems, I think that the overall architecture and management of data are much more interesting problems than the code. I feel like Go helps direct more of the thinking toward the overall rather than creating beautiful abstractions in the code.

We'll see if I still feel this way in a year.