I know my personal feelings, but I'm wondering if there is anything I'm missing. I've always wanted an iPhone but I'm second guessing myself if it's necessary. I like my Droid X but an iPhone is very appealing so please, sell me 
It's iOS pretty much (which is kinda sub-par to android 2.3-3.0)
But the main reason people get it is cause it's apple.. and maybe the display. The only reason I would get one is cause of the Ipod.. I don't like carrying 2-3 device on me.. kinda redundant
I couldn't say which OS is better.. both seem to be doing fine in the market so obviously both are good.
However, to me what sets Apple iphone apart from the rest is the build quality and detail in such a precise instrument. The materials used to build the iphone is outstanding.
That china doll glass on the iP4 is not better than the gorilla glass.
I'll break it down.
iPhone:
Android:
- Awesome build quality
- App Store. Really nothing compares to it.
- Uniformity. There's just one kind of phone, more or less. So everything just works.
- Lack of customization is a drag, but at the same time lack of customization isn't bogging down the system
- Tight OS/Hardware integration assures that you get the best User Experience.
- Variety of phones, most are made of plastic.
- For those cheap phones or the buy one get one free, you get what you're paying for. If you want quality, you need to spend as much, or more than the iPhone.
- The OS is fun, but clearly designed by and for Windows and Linux users who like to get their fingers in everything, no matter how convoluted it is.
- you can customize the interface at the cost of performance.
- Fragmentation, some apps will refuse to work on some phones or they won't work as expected.
- You're not completely dependent on the Android market for your apps, but you install apps at your own risk.
It may sound bias, but I am speaking from experience with both phones in my hand.