You don't get personal preference do you? That's like saying what does a BMW do that a comparable Audi can't? They'll both get you to where you want to go, but some just like the feel or how the controls are laid out on one vs. the other.
So to answer your question, it's the keyboard on the Z30 that does things the others don't. I've used the iPhone, Nexus and Samsung and I can type way faster on the Z30 which learns words you commonly use and displays them so you can simply flick to insert. The others don't have that feature. Considering how many texts and emails I send a day from my phone, the Z30 is a hands down winner.
So why would I choose a product based solely on the future of the company? I'm not concerned about Blackberry. It's a $100 phone and if they're not around a few years from now, who cares, I'll buy something else. Until then, I'll use the phone that best fits my needs.