I'd say, Android phones are many, but iOS phones there is just one. If you compared an iPhone to your average Android phone, the first would come ahead, but if you compare it to a high-end one they would be more at the same level.
As sliqua said, the device is important. I have personal experience with my father's iPhone, and I must tell it ran much more smoothly than any Android I've seen, but I haven't seen one of those new Samsung Androids that seem to be comparable with the iPhone in both capabilities... and price. If you like tinkering with your device, an Android gives more freedom, although you can always jailbreak an Apple product. There are also more apps for iOS, but the Android Market is strong and growing, and it may continue to do so in years to come.
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To build may have to be the slow and laborious task of years. To destroy can be the thoughtless act of a single day. - Winston Churchill