For years now Statvoo.com has been doing Website Analysis and Statistics, originally from it's Realtime Website Analytics origins over at https://analytics.statvoo.com to the overall stats it provides at https://statvoo.com.
A new Statvoo Ranking system has been implemented on each site it analyses e.g. https://statvoo.com/website/news.ycombinator.com under the "Website Ranks & Scores" subsection.
It combines numerous sources to come up with a final ranking system that is globally correct.
This metric is now available through an API over at if you'd like to test it out: https://statvoo.com/api/?domain=news.ycombinator.com&rank=true
It is also available as a Chrome Extension: https://chrome.google.com/webstore/detail/statvoo-website-valuation/fpgmelbdpbnlnhmgjiialmclenaiaadm
Give it a try!