Alright...
When I had the iPhone 4s. I tried the Samsung Galaxy Nexus..
Couldn't stand it.
My main woes
Native email client was LACKING. BADLY. Also became unstable with multiple mail accounts.
Once you got a decent amount of messages (I run a pretty big small business, I get 10-20K SMS a month, never mind the fact I use 3000-4000 minutes). The messaging app couldn't keep up, and was becoming unstable with a large load of messages.
Once I got a decent amount of stuff on the phone I found it lagging out very easily.
I didn't use it long, but I don't like to have to tinker with my phone, should work OOB for what I need it for. I do understand Android has come a long way since the initial ICS release though.
For me ESPECIALLY now.
My iPhone syncs with EVERYTHING. My production machine is a Mac Pro, SMS, Calling, notes, calendar, Safari, everything syncs. I can message and call people from my Mac. And respond much faster.
Something back in 2011 with the 4S that wasn't a big deal but is now, is FaceTime, FaceTime Audio and iMessage. I can message people internationally without causing myself long distance SMS fee's. Almost all of my intl clients have iPhones. I was able to kill my US and UK calling add-ons saving me 30$ a month thanks to FaceTime Audio, which I must say is also a lot more reliable for calling internationally. Also I can pick up the call on my Mac, which is perfect when my iPhone is charging.
Another thing on that point is when I'm traveling internationally, everything is kept in sync. Pop in a different country SIM if needed in my backup iPhone, my number from my main iPhone stays there, text, call through FaceTime/iMessage keeps my number intact and doesn't confuse clients or make me miss important information.
Simple backups/restores. When I get a new device its an easy "Restore Backup"
Everything just "works" on my iPhone, and works wonderfully.
Ecosystem Integration is a dream.
From a business-user standpoint, Android just wouldn't work for me.
I do know that theirs ways to get your Android texts and stuff on your computer, but the way the iPhone does it is built into OS X and my iPhone itself. The seamlessness is what keeps me here.
That and if I ever have a problem, I can walk into an Apple Store and walk out with a new device.
-TMacGuy