I have been slowly evolving the data core of each of my research projects from JSON to YAML. I'm still providing JSON, and even XML, Atom, CSV, and other machine-readable representations as part of my research, but the core of each project, which lives in the Jekyll _data folder are all YAML moving forward.
When I first started using YAML, I didn't much care for it. When the OpenAPI Specification introduced the YAML version, in addition to the JSON version, I wasn't all that impressed. It felt like the early days of JSON back in 2008 when I was making the switch from primarily XML to a more JSON-friendly environment. It took me a while to like JSON because I really liked my XML. Now, it is taking me a while to like YAML because I really like my JSON.
I do not anticipate that JSON will go the same way that XML did for me. I think it will remain a dominant machine-readable format in what I do, but YAML is proving to have more value as the core of my work, especially when it is managed with Jekyll and Github. I am enjoying having been in the industry long enough to see these cycles and be in a position where I can hopefully think more thoughtfully about each one as it occurs.