Rand Fishkin polled 132 SEO experts with data from over 10,000 Google search results, and have attempted to rank the importance of ranking signals. It’s not confirmed fact, obviously. Google won’t provide such information, but I suppose the next best thing is the collective opinion of a large group of people who make their livings getting sites to rank in search engines, and Fishkin has put together an impressive presentation.
The factors are actually broken down into the following subsets, where each is ranked against other related factors: overall algorithmic factors, page-specific link signals, domain-wide link signals, on-page signals, domain name match signals, social signals, and highest positively + negatively correlated metrics overall.
The results find that page-level link metrics are the top algorithmic factors (22%), followed by domain-level, link authority features (21%). This is similar to the same SEOmoz poll for 2009, but there is a huge difference in the numbers, indicating that experts are less certain that page-level link metrics are as important. In 2009, they accounted for 43%.