ptr has no online leaderboards that could be used as a data basis for this.
There used to be a guy who ran a site that would take pictures of the
top 20 and each of the top 3 player/players' gear/skills (aka 'Hero
Details' on right click) every few days for each category.
It was http://d.3utilities.com/ but is unfortunately gone now. But maybe you're familiar with it. Obviously this isn't in the Blizzard API at all, lol, and he probably manually took those screenshots every few days himself. Was hoping somebody would replace it with some kind of script to auto-screen+upload...