Simple solution for setting a default response data renderer:

1. Open the jMeter properties file (either the provided jmeter.properties file or your own version) in your editor

2. Search for "# Order of Renderers in View Results Tree"

3. Make the desired renderer the first entry in the view.results.tree.renderers_order property, i.e.

   1. change
      view.results.tree.renderers_order=.RenderAsText,.RenderAsRegexp, ... .RenderAsDocument,.RenderAsJSON,.RenderAsXML
      to:

      view.results.tree.renderers_order=.RenderAsJSON,.RenderAsText,.RenderAsRegexp, ... .RenderAsDocument,.RenderAsXML

   2. save the jmeter properies file

   3. restart jMeter