The document discusses the challenges of determining "top sellers" on a website to personalize the customer experience. It notes that brands currently show the same content to all visitors regardless of who they are. Determining top sellers is difficult as it needs to account for real-time visitor behavior, affinity, geo-trends, multiple signals, catalog changes, and more. Several dilemmas are presented, such as how to display top sellers from multiple categories equally rather than just one dominant category. An adaptive, machine-learning approach is needed to strategically determine relevant top sellers.