blackberry is better for typing email, but terrible for web browsing or other apps. iphone is great for apps, webpages and viewing email. I would prefer an iphone, but I get a blackberry free at work.
iPhone is more better choice as per its specification and its advanced features related to new technology. I'm also using iPhone 4S since last 4 months.
The iPhone has a slick interface, but a lack of being able to customize it. The latest edition of BB10 is quick, and can accept Android apps. It will also be used to communicate with other devices that use BB10, like your car, your refrigerator, your music player, etc.