And JSON is (almost) a perfect subset of yaml.
I've been using csv lately. It's reputation is overstated.
What I like is that it's far more compact than yaml or json and trivially pulled into sqlite for ad-hoc queries.
Another is that it makes streaming processing a little easier. Once you have a line, you know you can attempt to process it, and you can shard processing on newlines without a full YAML processor. Tools that work on newlines or tools that can just split on lines can handle the first level of JSON Lines output.
Or spreadsheets, to work out a plan, and then MySQL.