Small timer alert: I work at Verizon, and I like to believe that I'm not one of those guys that works there and knows nothing of the products he sells lol. I'm quite enthusiastic about smartphones and the slightly more "advanced" capabilities of them as I'm always looking to push my phones above and beyond what they were meant to do out of the box (Rooting, jailbreaking, whathaveyou). I, just like you, just want to get my money's worth.
Simply put, from a corporate standpoint many businesspersons choose to go the Blackberry route because of enterprise servers and the ability to mass sync calenders, contacts, etc. Additionally, E-mail on Blackberrys is "push" meaning that you receive it near instantaneously from the time it's received on your server to your phone rather than having to set your mailbox to constantly search and retrieve at set increments (Of course, this is more technical than my paraphrasing and there are workarounds for other devices). Other than that, there isn't much to be offered in terms of developer support and third party apps... For the most part the specs on BBs are unflattering, most likely because the target audience isn't the average consumer, though in recent time teens and the like made it trendy (BBM, anyone?). Makes no sense to me, if you're looking to social network and browse the web, Blackberry is not the phone for you. If e-mail is your top priority and you need it in real time, however, that's really the only justification for buying one other than the lesser price tag (maybe). I will admit, though, I miss BBM.
Android devices are def gaining momentum because there's a new Android phone every damn day. It's an open source operating system that's Linux based, and frankly, it offers a lot more freedom and customization. The Android market is exploding, but quantity does NOT equal quality. Of those numbers, a lot of apps are next to useless/gimicks/borderline spam. If you can root your Android device it opens up a whole new world of creative control and administrative access. Browsing is pretty quick in my experience, hands down better than the antiquated BB browser. The GOOD apps are worthwhile as well. If you're an average guy looking to do everyday things and stay connected/entertained during downtime, it's def worth a look. I have to stress though, ROOTING your Android is a must if you want to do it all. It's a refreshing escape from carrier limitations and software you might have issues with. If you're a believer in Google products, sychronization of contacts, photos, calenders, e-mail etc is pretty seemless. Makes life a whole lot easier in that department. (Gmail on Android is push, of course)
Windows Phone 7... We'll get back to that later lol.
iPhone: There are certainly more people on here more qualified than me to talk about iPhone, so I won't front lol, but I will say: I love the interface. So clean, straightforward, intuitive. Developer support is the big selling point here. You better believe if there's an app worth having, it's on the iPhone FIRST or on the iPhone exclusively. Either one of the two. Most likely though, even if the app in question is available on all major platforms, it's prob best supported on iPhone.
I'd be happy to answer any questions truthfully to the best of my ability if anyone has any!

Like I said, I'm a total geek and would know this stuff regardless of my employer because it's of personal interest to me. I'm best versed in Android/BB, but I'm resourceful nonetheless in regards to phones in general. As a community we can all help each other out here! lol