[boltzmann-brain]

Rust or Haskell. Python is subpar in terms of maintainability especially when it comes to long-running, generational, massive, codebases. Python is also massively worse when it comes to performance. Haskell strikes the perfect balance here, I've worked at companies with massive codebases where maintaining is still a breeze years later. This simply does not happen with any OOP languages, the code always turns into an ingrown hedge with time.

Especially when it comes to long-running projects like what's attempted here, Python, even being a technology from yesteryear, isn't even suited for problems of yesteryear.

With projects like these maintainability is your #1 concern, so referential transparency (greatly reinforced by laziness-by-default) and purity are indispensable and irreplaceable here.

The next concern is adequate performance, and Haskell has that in heaps.

The final concern is the capability to find programmers, and there are heaps of those in Haskell land.