Google's biggest ranking "buckets", according to evidence collected at its antitrust trial, are:

1. Topicality: How relevant is the page to a topic/query. Heavily determined by the "ABC" ranking signals:

• Anchors - the links pointing to the page

• Body - the text on the page

• Clicks - user click signals to determine relevance

2. Navboost: a re-ranking system that uses 13 months of user click data to adjust search results (first/long/last clicks)

3. Quality (Q*): One of Google's most important signals, based on site authority + quality adjustments (e.g., Panda, Helpful Content, spam)

SEOs—including yours truly—often get distracted by shiny things. But focusing on these three ranking buckets will likely account for 80-90% of your Google visibility.