Need to be able to facetime friends, family, and GF. Can't force them all to use Skype. Same goes with Messages and them.
Having items from my phone to my iMac always synced up, without having to fiddle with 3rd party programs.
Better warranty (in store), and AppleCare option, since the phone is on me when I cycle 100 miles a week.
The ability to plug in guitar/keyboard, and the music production apps that utilize it (JamUP, Amplitube, Ampkit, and GarageBand). My iPhone is essentially a 16 track portastudio that has replaced my tascam and zoom portastudios that costed hundreds and don't have nearly as much functionality.
Higher resale value, since I sell the phone on craigslist or eBay to help fund the next phone.
Don't need to run virus scans. I understand that viruses may be very rare on Android phones, but I always ran them to have the peace of mind, and because it was a necessary troubleshooting step when I was dealing with issues.
My experience with Android phones have involved my problems and quirks than my experience with iPhones. Though this is relative and other people may disagree.
Having Apple Stores supplementing any support I need. Sometimes getting help in person is far better than via phone or email.
Best selection of games. My iPhone doubles as a portable gaming console that I rely on when I have downtime. (Road trips, waiting at the doctors office)
I like touch ID and Apple Pay.
Best selection when it comes to accessories and addons.
No junk apps preinstalled. I'm always able to run the latest and greatest firmware in the 2 years, 2 generations I have my phone.
I prefer the style of the hardware.
I like supporting a company that is based in my state. Even though Apple's maufacturing is mostly in China like everyone else, the rest of the company like R&D are in the states. I don't know of any other smartphone maker that has their cell center in the states.