Before I get into what is better about an iPhone, remember that I chose a Nexus, so that should tell you a little something:
1 - The App Store is still better than Google Play. Play has improved leaps and bounds, but many Apps originate in the iOS system and then migrate to Android.
2 - The fit and finish of an iPhone is better than any Android device, save for maybe the Nexus 4. Obviously a couple of the Samsung phones are great, but they don't feel as much like a quality item. This includes the Nexus S. iPhones are very high quality phones.
3 - The iPhone screen is still better than most Android phones. I know you will probably spout off ppi numbers or whatever, but you can just tell by looking at the phone. (Note: I haven't looked at the Droid DNA yet)
4 - They are easier to use for the average user. I know this is a downside for a lot of people, but my Mom has a much easier time with an iPhone.
And, you can't use the "Apples cost more" argument for the iPhone - it just isn't true. Sure, you can make this argument for MacBooks, but an iPhone costs the same as the latest and greatest Android device.
On the other hand, there are A LOT of things that are better about Android, but I won't get into those here. Really, it comes down to personal preference.