At JUXT we use Clojure's EDN, bolstered with some tag literals courtesy of our Aero library (described here: https://juxt.pro/blog/posts/aero.html). We use ClojureScript to compile to TF's JSON. EDN allows comments, ignores commas and otherwise is a nicer JSON. Aero allows us to encode multiple environments in a single document, and include ciphertext for secrets. We're pretty happy with the overall result.