Ok, well first, I would disregard software differences, because as long as your phone can access the Android Market, and LauncherPro then you're fine.
Droid Incredible - Great form factor, optical mouse is very handy. Battery life is subpar, display is a bit oversaturated, but looks really nice overall. Nice 8mp shooter. not ideal for gaming due to its slow GPU-which is irrelevant if you're not really into gaming. The phone is very fast otherwise. Only has 3 LEDs for some reason(green, amber, red). Other Android devices usually have 7. Fully hackable, rootable, flashable, etc... If you're into that type of thing.
Droid X - large screen, great battery life, 720p video recording capabilities, takes nice pics. Has a GPU that can keep up with today's latest games and emulators. Definitely rootable, semi hackable, flashing alternate ROMs is sorta possible via workaround (someone correct me if I'm wrong) Has "Unicorn like" availability at the moment. So if you want to get a phone today, then you may be out of luck.
Droid 2 - Very nice keyboard which gives it a good combination of form and function. has the same internals as the DX, great battery life, shoots good video, but probably has the worst cam for pics out of the 3-not that its bad, just not as good as the DX or DINC, and it doesn't have a FM radio, or an option for TV output like the other 2. Has no hacks at the moment, however, the phone is already very fast, and runs 2.2 out the box. Its the only Android device that can boast such a feature thus far.
Other notes worth mentioning-
This hasn't even reached rumor status yet, but don't be surprised if the D2 gets access to 720p video recording whether it be via 3rd party hack, or an official OTA upgrade from Verizon themselves, after all, it runs the SAME EXACT hardware as the the DX.
The Droid Incredible runs HTC Sense UI. It looks very nice, but often runs into compatibility snags with market applications. I can't count how many negative comments I read on the market everyday about how "such and such" app keeps force closing on my EVO/Incredible/Desire/Hero/Eris. Then again, this all goes back to its "hackability" so you're not just stuck with the manufacturers firmware like the DX or D2. It would probably be my choice of phone if I could get over the battery life.