iOS has Apple's ecosystem, superlative design and engineering teams, and support behind it. It's simpler (good or bad), more responsive, more stable, and has some advantages over Google in features.
However, Android is packed to the brim with really advanced features. Some are going to be unseen and unused by the majority of consumers, but for die-hard tech geeks that require maximum control over their phone, Android is a must. From what I gather, anyways. I think it needs to be more user friendly, having some official aggregate for customization, more intuitive, and more responsive/polished.
They're both really good, just different. Google Now looks awesome, and some things on Android are more powerful and just make more sense (Notifications, Multi-tasking). I'm tempted occasionally, too.