Generally speaking. IPhones are great for personal use, as they cannot be managed centrally. Blackberry's are good for corporate use, as they can be managed centrally with a blackberry server.
It also depends on perference, if you enjoy a touch screen rather than physical buttons, then IPhone is the way to go.
Both devices will get the job done though and there really isn't a wrong choice. It's all up to your preference.
Hope this helps.