I've never played around with a Droid so can't speak to that one. I used to use an older model BB but recently changed depts at work so gratefully gave it up. I'm just not a big fan of BBs but I appreciate their functionality. Build quality is lacking for one thing IMO. If email access is your most important requirement I think the BB is the better bet. I work at home most days with my work laptop, personal desktop and personal laptop in front of me so I access my personal web email from my laptop whenever I need to.
I went with the iPhone 3G back in Oct 2008 and have had no real issues with it, other than dust getting onto the inside of the screen, likely from the opening where the connector is at the bottom of the phone, since it's in my front pocket a lot of the time. I've never had, or heard of any real issues with cracked screens or any other issues for that matter, with the iPhone.
The BB on the other hand, is a different story. My wife's gone through several in the last 2 yrs. She had an original Bold which was replaced due to trackball issues and the back cover not staying on. She got a new Bold (8700?) with the trackpad and has had issues with that too. She also has an identical Bold from work (yes she walks around with two Bolds all the time now!) and that one had some issues as well.
If you want something for making calls, decent calendar, killing time, etc, the iPhone is my choice. The Google Maps app is great. I use it a lot especially since my Garmin Nuvi tends to send me on wild goose chases sometimes. The internet browser is superior to the BBs IMO also.
The other thing I like about the iPhone is it's integration. When you enter addresses or ph#s in the calendar for example, it hot links them so you can just tap the address, ph#, etc and make the call directly, or go directly to Google maps. No need to copy and paste the address or ph# into the appropriate app to make the call or look up the address on the map. When someone texts you a ph# you can automatically add it to a new contact or existing contact, etc.
I'm waiting for my buddy who works at Rogers Wireless (Canadian GSM provider) to let me know when he gets more 32Gb iPhone 4s in so I can go pick one up. I've played around with one and it blows the 3G and even 3Gs out of the water. That retina display for one thing is amazing. I truly can't distinguish pixels on the screen. I've seen pictures and video from the HD camera and am quite impressed with the quality.
As much as I hate how iTunes works on Windows machines I'm gonna stick with iPhones for now.
Sorry for babbling, just wanted to give my perspective to help you with your choice.
Cheers!