I detailed a comparison of OPA and Cedar with verified permissions here: https://www.styra.com/knowledge-center/opa-vs-cedar-aws-veri...
Universally, people I've met and worked with (20-30) hate writing rego (OPA).
I'm always skeptical of Styra's analysis; they are literally selling you something.
AuthZed looks interesting and they have good "ride along" videos in YouTube, e.g. replicating GitHub auth.