Interestingly, I've become a big fan of node's single-threaded "one big loop" model, which means multitasking is cooperative instead of preemptive. This strikes me as more honest, somehow. It doesn't distract you with abstractions (like threads) that don't make sense in this context. Most production workloads these days will be a docker process assigned to (at best) a single sticky core/thread on a blade somewhere - so in terms of resources, node is quite honest about what you actually have to work with. (This as opposed to, say, a Java process, which wants to believe it has control over an entire physical server CPU, and when you run it in a docker process, you're just exercising virtualization overhead if you use Thread, etc.)

That said, if you have a physical server, Java is quite good, especially with the upcoming Project Loom improvements. The langspec and vmspec have gotten fat the last 20 years, but at least those documents exist. Plus there is OpenJDK which is a great enabler and calmer of nerves; there's a reason so many alt langs target the JVM, and they are good. Groovy, Clojure, Kotlin, Scala are all first-rate languages, IMHO. And with projects like Quarkus you can more easily build native executables that bundle the JRE and make distribution very Rust-like.

Another environment I like specifically for async operation, but mostly by reputation, is Erlang and it's BEAM VM. Erlang itself is such an interesting language, being dynamic, functional, immutable, without traditional control structures (!) but relying heavily on recursion and pattern matching, and of course the "actor model" and extremely lightweight "processes" was invented here (and promptly ported to elsewhere, as with Akka). It was also created by one of the nicest human beings I've ever experienced, Joe Armstrong, may he rest in peace.

IANALL so YMMV.