YMMV of course, but the thing that makes iOS stand out for me is the stability, the Appstore (Google play is absolutely awful), the seemless way it integrates with my iMac and iPad (I have a windows machine too just in case you were wondering ), and above all, the timely updates.
If android can sort out the update situation and they can get Android stable over various devices, then maybe I'll think about switching back.
As it is though, the iPhone just oozes quality I find lacking in Android at the moment.
+1 This is ultimately what led me from Android to the iphone - the quality of the experience. Android has a lot of pros, but the ultimate user experience, from the ecosystem with my imac at home, to the fluidity and crispness of the UI and apps, is offerred by Apple and ios. As they say "It just works."