iPhone users are more loyal to Apple than users of any other smartphone brand are.
According to data from Morgan Stanley's AlphaWise tracker, which compiles sell-through data using web search analysis, 90% of iPhone users stick with the brand when purchasing another phone. Samsung, Apple's largest competitor, managed to improve its brand retention rate significantly over the past years, but still trails Apple by 13 percentage points.
This chart shows the brand retention rate for selected smartphone vendors.
You will find more statistics at Statista