Depends on what you are going to use it for. If you need to push corporate email, blackberry RIM is the way to go and the pearl is the most compact of the blackberry devices. The half-qwerty with suretype is pretty good too.
Although the BB Pearl does have multimedia capabilities, the iPod is obviously better for both music and video, especially if you already have an extensive iTunes library.
As for browsing, the iPhone has a full web browser, while the pearl is restricted to mobile WAP pages. In addition, the iPhone has wifi, so it can browse most webpages, even high bandwidth ones without a hitch.