Perry Bernard: When Google says they "prefer JSON" they do not mean it gets better ranking or indexing compared to Mircodata. What they mean is that if you have an item marked up with both JSON and Microdata, Google will ignore the microdata version.
Stockbridge Truslow: I`ve never been able to quite figure out why Google prefers JSON over RDFa or Microdata. My "guess" is that it creates a redundancy that can be validated. The elements, for example the price, appear twice on the page - once in the JSON and once in the price listing on the page. Google can then validate the data in the JSON and match it up against content. With Microdata/RDFa, the price on the page is marked up to be the product price and there`s no verification.
(This also makes it important to get all the data in both places).
RDFa and Microdata work fine, though. In some cases it`s a lot easier/cheaper to make... you just cobble together a template, put the variables in the right place and you`re done. With JSON, you need the template for the html, but you also need something additional that`s going to spit out the JSON code.
মোঃ কামরà§à¦œà§à¦œà¦¾à¦®à¦¾à¦¨: I think also, it`s create duplicate within the contents and it can provide false information to search engine. so that still I`m using microdata enabled themes.
Roger Montti: JSON-LD does not mess with the HTML. It`s a script that can be placed anywhere in the code. It`s easier to use.
If you know how to look at code then it`s pretty clear that JSON-LD is hands down the easiest and best form of structured data.
Perry Bernard: Google recommends JSON but reads both with no ranking bias between one or the other. I have noticed that it can read mixed data, so that if some elements are noted in JSON, it can read others from Microdata at the same time and blend results, but not all, and this may not be evident in the Structured Data Testing Tool, but blended results are reported in GSC. I recommend you universally use JSON for greatest simplicity in management.
Roger Montti: And Google stopped supporting data-vocabulary.org structured data, which was Google`s implementation that was eventually superseded by Schema.org.
Which schema markup good for SEO? 
