The fact that you are postibg this on BlackBerry forums might result in biased results. Let me add a bit of insight on this.
The BlackBerry phones are designed for serious use. If you receive a lot of e-mail then you should consider that. However, it's not a boring old phone. It's got games too, although not nearly as much as the iPhone.
The iPhone is very different. It's pretty much any old dumbphone with iTouch slapped on. For e-mails, it's awful. It receives e-mails up to 2 days after they are sent, to start with. Secondly, the touch keyboard is awful, even when horizontal, On the upside, it does keep you company when bored, although a social giant like myself benefits from BBM much more.
Yeah the apps are fun but after you play them a good five times they'll only take up space.
The final thing to mention is the battery life. The iPhone only lasts for about a couple of hours before it runs out. If you're out and about, then it will surely slow you down.
You said that only 2 of your friends have a BlackBerry, but that's okay. Apps like WhatsApp are still on the BlackBerry so you can chat to your other friends without losing a good phone.
I've seen both. I own the BlackBerry Curve 3G and it's splendid. My mother's got an iPhone, and for me, it's wearisome. For me. All in all you should check both out first before making a decision. I spent a month looking them up.
Posted from my CrackBerry at wapforums.crackberry.com