Here's an idea - why don't you ask your BB fanboy friend why he thinks you should get a BB? Maybe he has good reasons. Maybe there are no good reasons. Or maybe he's got a good argument for somebody other than you. Honestly do you think that one phone is better than another for the same reasons as everybody?
BB has a real keyboard, support for microSD cards, USB mass storage, BBM and a user replaceable battery.
iPhone 4 supports your current apps and media and offers Apple branded quality.
You can't ask other people to tell you what phone to want before you tell them what you want out of a phone.