The most sold product Apple was not the iPhone. This is evidenced by research conducted by Ceros with coverage in the last few years.
In 2016 the most popular Apple product was the Lightning USB cable because the cables Apple has long been a sore spot and often ground. In 2017 became the leader of the adapter with a Lightning to 3.5 mm headphone Jack when a connector is missing in the iPhone 7 and 7 Plus. But at the moment it is best to sell AirPods wireless headphones from Apple.
In their study, the Ceros took into account the data of Best Buy, the largest retailer of electronics and home appliances in the United States and Canada.