There's no clear answer to this question...
The HTC Incredible has the Sense UI, which some people really like, as well as a fast Snapdragon 1GHz CPU and twice the RAM as the Moto Droid. The phone also has a good 8 MP camera, which can record OK video as well.
The drawbacks of the HTC Incredible vs Moto Droid:
1) No QWERTY keyboard (I think this is a pretty big deal, because the QWERTY is very useful for many things like control in emulated games).
2) Many games are optimized for the iPhone hardware's PowerVR GPU, which means that if a game is ported from an iPhone 3GS it will run significantly better on the Moto Droid vs Incredible / Nexus One unless significant optimization is done.
3) Inferior battery life.
4) You can't see the display worth a damn in sunlight.
5) Sense UI will mean that you'll need to wait for the 2.2 update longer. 2.2 having some pretty significant performance and feature improvements!
6) The build quality is kinda plasticy.
7) Less mod community love.
Pros:
1) Slightly more responsive in the main UI. Possibly due to faster CPU.
2) Slightly superior camera, and superior camera software.
3) Display colors are vibrant in indoor lighting conditions.
4) More RAM could help performance in future apps.
I probably come across biased toward the Moto Droid... and I am, since I just purchased one recently. That said, I spent a lot of time deciding between the Moto Droid vs HTC Incredible, and feel good about my decision. I have had a blast with my Droid... and having used it for a little bit now, I can say that the QWERTY is very useful to me, for both productivity and fun.