At the time of buying my Droid X, there was no iPhone for Verizon (7/15/10).
I just recently switched to an iPhone 4 for Verizon. Why? Because everything else sucks. Literally. Let me elaborate on that.
First off, Blackberry. Great phone at first, but overtime it began to freeze A LOT. It's slow, the app store is pathetic, and BBM gets old pretty quick. The low resolution tiny screens and plastic feel gets to be of an annoyance.
Second off, Android. My Droid X was great, at first. I loved that phone, the gorgeous 4.3" display made viewing web pages extremely easy. The app store was okay. Over time, the updates made the phone worse, and Google could give a **** about being quick to fix it. My phone went from awesome to a piece of ****. It froze, all the time. Random service drops when I had full bars, web pages didn't load even though I had full service, it would take black pictures, the camera gallery always crashed, the phone itself became slow even after multiple resets. The wow factor of the screen size wears off too. Oh and as for flash player? Yeah, it's extremely laggy/choppy and crashes all the time. You have to be on wi-fi for it to actually be usable. To top it all off, the speaker on the Droid X is unbearably low, crappy quality, and just a joke in general.
After a year of having my Droid X, I switched to an iPhone (6/5/11). It's only been a few weeks, but I love this phone. The screen is so fantastic it's insane. The colors are amazing, and the pixel density is crazy. It's beautiful. The build quality is also fantastic. It's high quality glass, encased in aluminum. It's ultra thin also. The design is extremely unique, you can tell a lot of work was put into it. It feels very high quality. The speaker on the phone is loud too, which is a bonus. The OS is awesome, I actually like the way the notifications are delivered, I have no complaints about that. The apps are far better than Android's too. The front facing camera is VGA, but pretty good quality. The back camera is simply amazing at 5 megapixels. Very good quality (I own a DSLR, and this phone has really good picture quality). It's fast too. No slow downs. All in all, this phone is amazing, and IMO, the best one out there.