I've had the Storm, Storm 2, Droid, and now have the Incredible. When I tried the Droid X, I quickly became aggravated at how inaccurate the screen is. I would try to tap a link on a website and find that the phone thought I tapped the one next to it. Then when I tried to play Carrom 3D (a billiards game) on the X, I noticed that when aiming, as soon as I took my finger off the screen, the aim would shift a little.
Maybe my fingers are too big or the screen is that inaccurate, but I never have that problem with the Incredible. I can even tap the tiniest of links (like forum page numbers) without zooming the page. This is all without any screen or keyboard calibration (the latter found in the Incredible's keyboard settings; don't know if the former exists).
There are other things I liked and disliked about the X. Dislikes were mostly the screen's accuracy and it wasn't LED (I'm spoiled there), but I did like the size of the screen and how easy it was to type in portrait mode - something I have trouble with on the Incredible.
I'm hoping the Fascinate will be the best of both the Droid X and the Incredible, and then some.
You really should go into a store and compare both models yourself to see which one is best for you. In the end, everyone's personal tastes are different. Then again, there is always the 30-day "trial" period. If you don't like one, return it for the other within 30 days.