Well, while I do think BlackBerry makes great devices... You should go with the iPhone. Altho, it does depend on what you need.
The iPhone comes with an avaliablity of 50k+ apps.. The BB appworld er w/e doesn't have nearly as many. The iPhone has a giant touchscreen.. The BB has a very nice hardware QWERTY (personal preference, imo).
More importantly: apple will release updates for the iPhone for a very long time. The interface is tested, and it's one of the best. While I hear that BB is exteremly stable and nice looking, it's cluttered, and idk how long it'll be supported.
So rly, it's what you want: a lil piece of plastic, or a huge glass screen