Just from the top of my head, a few come into mind:
A. Security.
With iPhone, if yo do not jailbreak, you can have high confidence that applications that you download would not steal your data. You can't have the same assurance with Android, where Malware and dodgy applications in the official market place is a hugh problem.
B. Customization.
I know many will protest strongly when reading this, but it's fact from the viewpoint of normal users. ( not talking about hackers here, whom I'm sure would love the ease of doing anything they want to they phone). Android's firmware are divided into many region, making it difficult to combine any languages you want in the same phone. If I'm in Australia, I can't use my phone in Chinese like I could with iPhone without changing ROM. (not just talking about keyboard, but have the UI in Chinese).
If I want feature A (e.g., some special feature of HTC), I can't at the same time have the feature I like in Samsung since I can have only one ROM at a time.
In contrast, a jailbroken iPhone's approach of customisation is always installing a program to the single version of stock firmware, hence customisations are not mutually exclusive to the other customisations.
There are customisations which can only be achieve in iPhone but impossible on Android. One such customisation is to skip/repeat/start/stop music and media using hardware buttons (I use long press volume button to skip/repeat, and long press home key to start/pause media). I can perform this without leaving another application, or on home screen, or on lock screen, or when the phone is asleep.
C Integration with iPad and PC
If I create a Safari reading list, it shows up in the iPad and iPhone. If I save a bookmark, all three of them are synced via iCloud. If I take a picture with my iPhone, it shows up in the iPad and the PC wirelessly. If I create a contact, it get added to the contact on the iPad and Mac via iCloud. If I read an eBook on the iPhone and put the bookmark on the page, I can see that on my iPad. I know this is also done a certain extent with Android, but the integration with iPad and PC is far tighter with iPhone.
D. Consistent user interface.
You can have a consistent way of doing copy and paste, but you can't have that on Android.
E. Ease and assurance of firmware upgrade, quality of firmware
You can concentrate on using the phone, not on flashing ROM just to keep updated and to patch issues.
F: Availability and quality of application
Depends on what your requirements are, the seriousness differ. In my case, I still have about 5 applications that I absolutely must have but are still unavailable on the Android platform. The same applications also tend to be of higher quality on iPHone than on Android. I have a golfing application called GolfCard Pro, for example on both my iPhone and my Samsung Galaxy S. The one on SGS is laggy, does not support sharing of golf score with my buddies using HTML mail (since HTML mail is unsupported in Android, according to the software vendor).
G. Multitasking the way I want it.
With Android, I often find applications re-starting on their own, after I have killed them. It is more difficult to manage compared to iPhone's.
H. The little things
I just much prefer all the subtle little things in iPhone's UI, such as the feedback sound, the shape of the icon, the manner speed/style of scrolling. I dislike Android's back button which is suppose to bring you back to the previous function (although many applications also duplicate that process but a button on the screen, like the iPhone's way), while other times, it kicks the user out of the application all together causing frustration. You can't customise the phone to disable the accidental kicking out of the application, unfortunately.
