The only thing i like about BBs is their small compact form factor with great qwerty keypad.
Then again I never owned one. I find it to be a bit boring... maybe when I'm older.. hehe
Iphone is a great multimedia phone. I used to bash it for its really limited functions way back to iphone 2g. but Ive been using the 3g, 3gs, and 4g. And I swallowed my words and switched all because of the great apps in its Appstore.
After 3 years in the iphone world, I found myself swaying to Android because of its great tweaking open system.. Apps-wise, it is getting there with Apple as Android has gained more and more footing in the mobile market. I started off with the Motorola Milestone 1 to get a taste of the Android feel. And Im now using the Samsung Galaxy S2.
Whichever platform you decide, Im sure you will enjoy their own niche. Its going to be an investment as well especially if you buy apps and games.