I know it’s kinda cheap, but for me nothing is the answer (that includes hcl). I’ll use what I find, but I can’t say that I love anything.
If something uses toml, I will use toml. I’ve also used json-schema in the past.
Depending on what I do I find yaml and kustomize okay, etc.. Using something like client-go has its advantages as well.
If I am building something from scratch then I would reach for a simple ini. I feel like everything else overcomplicates things and that’s usually a symptom for something else.
ChatGPT is a great clippy replacement for spellchecking and grammar.