Hm I never heard of Rune, and I have heard of all the others (although this article gave me more info about Val):

https://github.com/google/rune (side project, not Google project)

This part is interesting, as I've found many benefits from having a layer of indirection between the app-level data definitions, and the C/C++ struct level. I recall that Jai used to advertise the SoA -> AoS transforms but that was many years ago.

It provides many of its features by deeply integrating the "DataDraw" tool into the primitives and constructs of the language. DataDraw is a code-generation tool that generates highly-optimized C code which outperforms e.g., the C++ STL given a declarative description of data-structures and relationships between them. For more information, see the DataDraw 3.0 Manual.

I've never heard of DataDraw either .. I wonder who uses it?