Let's say I wanted to build an algorithm that would rank websites/brands based on how important, influential and successful they are. What public, numerical metrics could I use that would be reasonably defensible?

I think Compete, Quantcast (unless Quantified), Google Trends for Websites, Hitwise, Alexa, etc. are all terrible due to accuracy issues (see http://www.seomoz.org/blog/testing-accuracy-visitor-data-alexa-compete-google-trends-quantcast).

Currently, I'm considering:
-> # of searches for the brand name according to Google AdWords
-> # of mentions of the brand name in Google News
-> Domain Authority of root domain via Mozscape
-> # of linking root domains
-> # of subscribers to their RSS feed (via Google Reader)
-> # Facebook fans
-> # of Twitter followers

Any other suggestions? I'd hope for metrics that are relatively indicative of overall influence, not just effort in a given channel (which makes Twitter/Facebook/RSS more questionable).
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