They are completely different tools.
BLACKBERRY
1. BB is the king of email. Even with the hardware keyboard, the Tour is the best device if you do a lot of email.
2. Stable OS. Most things just don't crash. It's rock stable.
3. I miss the hardware answer and end call buttons. It's wonderful to just know you'll be able to answer and end calls reliably.
4. Great Outlook compatibility.
DROID
1. If you do a ton of web surfing, the current Tour doesn't hold a candle. Next version with touch screen will be better.
2. Reading documents is wonderful - very high resolution screen, horizontal mode makes viewing PDFs great, even at small sizes.
3. Battery life is atrocious.
4. Operating system is flaky and add-on applications means many crashes per day.
5. Google sync and voice - great. Outlook compatibility - ridiculous, absurdly bad.
6. Good/bad: Many great apps, much larger and much cheaper than Blackberry, some still very immature in stage, e.g. Facebook.
Bottom line: They both get the job done. Blackberry is still the premiere business and power emailing tool. But if you do a good amount of web browsing (I do for work) and coupled with all the apps, it's a great experience if you can deal with the crashing and incompatibility.