The Galaxy S and the iPhone release schedules are out of lockstep, so each gets a shot at sticking around at the top level for at least half of the year. This season, the new Samsung Galaxy S7 lands right in the fast lane with the iPhone 6s already at cruising speed. Come fall, the lanes will change but the chase will continue.
Source: http://www.gsmarena.com/galaxy_s7_vs_iphone_6s-review-1415.php
