I haven’t used Neon, but from reading the docs, napi-res looks nicer. You add a single macro to the function you want to expose and everything else just works. You don’t even need a special JsResult like Neon uses.
Neon predates N-API so it couldn't use N-API initially. That's why NAPI-RS was written. Neon now finished migrating to N-API.
Who else thought they were talking about the Linux kernel network driver NAPI? ("New API")?