If your primary focus is email and business-grade communications: BlackBerry
If your primary focus is multimedia: iPhone.
Each is the king of it's genre. Each can dabble in the other's primary area of expertise, but that's not optimal. I found myself using different devices (other than BlackBerry) and trying more and more to make them behave like BlackBerrys. Big mistake, much frustration. Use the right tool for the job you're doing.