I have owned the Dinc, Fascinate and DX. I got the Dinc on launch day, it was my first Android phone. I have to say screen & sense were the big draw for me. The build quality just felt cheap to me (personal view) but I like HTC hardware. The downside was the battery and try adding a real extd battery from say Amzer or Seidio etc and it becomes a real porker in physical size and weight. The lack of app memory was also a downer to me at the time, running 2.1. Still a solid phone that I enjoyed (sold it for the iPhone which I now see as a bad, bad move).
Sold off my iPhone and returned to Verizon after I tried the Captivate, which I felt was a bad implementation by AT&T but felt the Fascinate was worth a try, and the form factor was much better. Gorgeous screen, still not take with, Sense is still better than Touch Wiz. But the the screen was almost too shinny & vivid it made the colors seem almost candy store like (to me at least). Less memory (thanks Verizon), Bing is fine, but fine IF I chose it, not if its forced on me. I returned it after about a week, it was almost too thin and slippery for my taste, plus the location of the power button was pain.
The Droid X, I actually thought the buttons would be annoying and cheap and it had turned me a way as I passed by it to get the Fascinate. Then I spent some time reading users opinions, reviews (multiple sites) and talked to a friend who migrated from a BB Curve to the Droid X this summer, he can't stop talking about it. He is not a super techy type and had never used Android before.
So I gave it a roll, and the buttons are not as cheap as I had thought (Best buy only carries dummy phones, so I played with one at a VZW store). I was surprised, the screen is awesome, sharp, good color, but not super in your face colors (yes some like that I don't). The on board memory was nice, the RAM to run the apps was nice and Moto Blur can be replaced by LP+. I got it yesterday so I haven't really had time to delve into apps and really play with it, but the CALL QUALITY ROCKS. Much better than the iPhone (go figure) and much better than the captivate, in fact I was able to continue a call right into my garage which is normally a 1-2 bar signal and choppy voice on the Fascinate. The Droid X did it all and then some.