It really is a subjective matter of preference. To one person, the DX may be superior, and to the next, the Fascinate. It all comes down to what you want, and which phone meets your needs best. Here is a technical breakdown:
[table="head;width=400px"]
Feature
|
Fascinate
|
Droid X
OS|2.1|2.2
Screen|SAMOLED 4"|WVGA 4.3"
Camera|5.0 MP|8.0 MP
Memory|512 MB RAM, 2 GB Internal|512 MB RAM, 8 GB Internal
Standby Time|Up to 312 hours|Up to 220 hours
Usage Time|Up to 420 minutes|Up to 480 minutes
Email|Yes|Yes
Web|Yes|Yes
Hotspot|Yes|Yes
QWERTY|Virtual|Virtual
Size|4.92H x 2.53W x 0.39D|5.02H x 2.57W x 0.39D
Weight|4.16 oz|5.47 oz
Battery|1500 mAh Li-Ion|1540 mAh Li-Ion
SD Card|16 GB installed|2 GB installed
Processor|1.0 GHz|1.0 GHz[/table]
Edit: Been having some issues today with the tables BB code... Sometimes it wants to work, sometimes it doesn't. YMMV.