Parrot Analytics is a bunch of hogwash IMO. Most of their findings is based around social media posts, online searches, torrents/downloads, and a whole bunch of other weird metrics to determine how "in-demand" something is. It says nothing about raw viewership or ratings, and these "in-demand" lists are hit by fanboy-driven shows with huge online fandoms, because those are much more linked to popular brands that people stan for. I will forever be baffled people, including journalists, taking this seriously.
Nielsen's methodology is also far from perfect, but their way of doing it is arguably the best. It tallies the actual minutes watched and gives a much better indication on what people are actually watching and what is actually popular with people.