The iPhone was first released on June 29, 2007. It is a line of smartphones designed and marketed by Apple Inc. The iPhone line includes the 3G, 3GS, 4, 4S, 5, 5C, 5S, 6, 6 Plus, 6S, 6S Plus, SE, 7, and 7 Plus. The iPhone runs Apple's iOS mobile operating system. The Droid was first released on October 22, 2009. It is a line of smartphones developed by Motorola Mobility, a subsidiary of Lenovo, and marketed as an alternative to Apple's iPhone. The Droid line includes the original Droid, the Droid 2, the Droid X, the Droid RAZR, the Droid RAZR Maxx, the Droid Bionic, the Droid Razr M, and the Droid Turbo. The Droid runs Android, a mobile operating system developed by Google.
There is no clear-cut answer, as both the iPhone and Droid have their own advantages and disadvantages. Ultimately, it depends on what features are most important to you and which phone fits your needs and budget better.