(Leaving aside thoughts on language syntax, compile times, tooling etc - just interested in people's experiences with / thoughts on healthy stdlibs)
Python (decent standard library) - It's pretty much everywhere. There's so many hidden gems in that standard library (difflib, argparse, shlex, subprocess, cmd)
C#/F# (.NET)
C# feels so productive because of how much is available in .NET Core, and F# gets to tag along and get it all for free too. With C# you can compile executables down to bundle the runtime and strip it down so your executables are in the 15 MiB range. If you have dotnet installed, you can run F# as scripts.
Do you worry at all about the future of F#? I've been told it's feeling more and more like a second-class citizen on .NET, but I don't have much personal experience.
As someone with all the memory of a fruit fly, I love a good REPL when I'm trying to recall the various magic incantations that make the computer go.
And there's plenty of libraries you'll have to pull to get a viable product.
Our React projects are the contrast. They live in total and complete isolation, both in development and in production. You're not going to work on React on a computer that will be connected to any sort of internal resources. We've also had to write a novel's worth of legal bullshit explaining how we can't realistically review every line of code from React dependencies for compliance.
Anyway, I don't think JS/TS is that bad. It has a lot of issues, but then, you could always have written your own wrapper ontop of Node's fetch instead of using Axios. Which I guess is where working in the NIS2 compliance sector makes things a little bit different, because we'd always chose to write the wrapper instead of using one others made. With the few exceptions for Microsoft products that I mentioned earlier.
Being tightly coupled with MS already, did you ever explore .NET?
It's been a while since I worked with an "actual" function app in Azure. We did have a few .NET ones that weren't using containers. At the time they were pretty good, but today I'm not sure what the benefit over a managed container envrionment with container apps would be. Similarily with sqlserver. We use it because of governance and how it ties into data factory and I guess fabric, but we don't use ORM's so something like Entity Framework wouldn't really be something we'd benefit from with .NET.
I think the only thing we couldn't realistically replace and get something similar is the governance, but that's more to do with how Management Groups, Policies, Subscriptions and EntraID works than anything else.
Eventuallyt everything will probably be Python and then C/Zig for compute heavy parts. Not because Python is great, it's terrible, but it's what everyone uses. We're an energy company and with the internal AI tools we've made widely available we now have non-SWE employees writing code. It's Business Intelligence, it's Risk analysys, it's powerplant engineers, it's accountants. They're all working with AI code in their sandboxed environments and it's all Python. Since some of it actually turns out to generate great value, it's better for us (and the business) if our SWE teams can easily take over when "amateur hour" needs to meet operational compliance for the more "serious" production envrionments. I put things in "'s because I'm still not entirely sure how to express this. A lot of what gets build is great, and would have never been build without AI because we don't have the man power, but it's usually some pretty bad software. Which is fine, until it isn't.