China’s delivery firms have surged thanks to the nation’s e-commerce boom. But S.F. ­Express, a subsidiary of S.F. Holding, has emerged on top. Group revenues in the first half of this year rose 32.2%, and analysts predict 20% future annual growth. The premium courier service distinguishes ­itself by retaining complete control over its delivery network rather than adopting a franchise model. That network includes a fleet of aircraft, and S.F. Express is investing in drones, too, nabbing China’s first government-issued drone delivery license this year.