To help with your decision, you can go online and view the phones and have them compared with each other in order to determine which better suits your needs. You can click on the link below to access and compare the device.
Its really a matter of personal preference. I can't comment on the DROID 2 or Samsung because I've never used either of them. I have an Incredible and I love it! It does it all, and I couldn't be happier. I tend to be a bit of a "phone hopper" - I seem to get bored with my phones in about 6 months and then I get another one. But I can't see me switching anytime soon. I used to be a big Blackberry fan, but once I switched to Android, I never looked back. I thought I would miss the physical keyboard, but it didn't take long to adjust to the virtual keyboard at all.
I always recommend that if you are still looking for a phone, go into the Verizon store and play with the display phones - and take as long as you like, I mean like a good hour or so. Don't let some store lacky push you around. These phone are too expensive, and you are making too big a commitment to feel pressured into making a decision in 10 minutes. And if you still aren't sure what you want, take a day or two to think about it. The phones aren't going anywhere!
I have had both the samsung and incredible. Also had the first moto droid and i like the fascinate the best because of the screen size and how clear the amoled screen is. the incredible may be a little faster but not noticeable. i personally dont like motorola. so if you like the bigger screen go with samsung.