According to two different seo studies conducted by Ascend2 and Searchmetrics valuable content has become of higher importance to search engine ranking than one year ago. The emphasis in on valuable content aka relevant content. Such content today is part of seo and no more just a nice supplement to websites.
Further revalued factors are user signals. Such factors are click through rate and time spent on a site or vice versa the bounce rate. Pronounced as well is the preference of brands. This does not just concern big players but niches in the same way. The latter may be seen in the context to valuable content mentioned above. Further information about the up to date Google ranking factors is given by the article Search Ranking Factors Data Points to Importance of Quality Content.