Depends on what you need. Both have solid hardware, good media support, and a very stable OS.
The Iphone is trendy, easy to use, integrates seamlessly with other Apple products, great browser, most mobile apps than any other device. It won't allow you to download large files or do video calling except through wifi. Also, video calling can only be done between Iphones, so if your friend has a different video phone like the Samsung Wave you can't do that with them. You also can't customise the phone the way you like it, unless you jailbreak it. It's also a data hog.
The Torch has all the Blackberry features: secure push email, better browser than the previous BB's, data economy through compression ( you can do more with 500mb on a BB than on another device), built in instant messenger, hardware keyboard and touchscreen keyboard. The Desktop is very customizable, and has native support for office files like excel, PDF, and PPD. You can remove the battery and also swap out the microSD card to increase memory. The touchscreen is a little too sensitive, and I found it a little top-heavy when typing. Not as many apps as on the Iphone, but still more than enough.
All in all, I prefer the Blackberry. I don't like Apple's "Let the experts worry about the tech, you just enjoy" mentality. I also prefer the features on the Torch, especially the physical keyboard, in case there's an issue with the screen.