Which is better JSON-RPC or JSON-REST?

Regarding JSON-RPC vs JSON (Rescript) here is some guidance, on balance JSON-RPC is likely to provide the best approach.

If you want to use batch requests (multiple API calls combined into one HTTP request) then JSON-RPC is the best method, if not either JSON and JSON-RPC would not make any difference except parsing response and constructing the request.

With JSON you might need to use different end points for different operations with JSON-RPC you can use same endpoint, specifying the operation in the payload.

JSON-RPC allows JavaScript clients to be written, like the visualisers, so again allows for simple thin web client interaction. We expect that JSON-RPC is the default preferred approach for most clients.