TOML is probably my go-to these days.

I think where TOML shines is when your configuration schema is relatively flat and simple. If you want to heavily nest configuration it can quickly get difficult to read. I’d love a more limited version of TOML that restricts the nesting depth.

There's a comparison [0] where some differences are explained.

[0]: https://github.com/soml-lang/soml/blob/main/comparison.md