So in terms of the mainstream languages, what would you say would be the most ideal language? (At least until Oct takes off!). Perhaps modern Java? .. Or even Zig?

C#, only because of dotnet ecosystem and tooling is great. TypeScript is a dark horse candidate, it's a great language with a great ecosystem trapped by JS tooling, and most of all, NPM. Rust is fine if you just tell LLMs to use short borrows only. I wouldn't even say Oct is the most ideal language, it's pretty good at getting LLMs to do science, but probably isn't the right language for all applications.

I have some very heavy criticism for Zig technically, because their whole thing about "no hidden control flow" becomes "shove all the hidden control flow into a second hard to debug runtime that runs at compile time", and manual allocation for everything is incredibly tedious and hard to keep track of in production code. I mean, C++ wasn't ALL wrong, there was a reason that templates exist in the first place, and having the entire generics model be just comptime isn't really a decision I agree with. The way I see it, Zig would probably find a niche as a language that configs C/C++ codebase at compile time instead of the C replacement they want it to be.

There are two more languages I have in the Oct repo, SDSL-V for SPIR-V shader/compute kernel authoring and Concept/Vulkan because the 20k line C Vulkan Prometheus runtime for GPU compute that we built is getting kind of unmaintainable even by AI that making up a new programming language to strangler fig refactor it is honestly the least bad option.

For what purpose? Different use cases require different language features.