Here are my personal observations and preferences:
Incredible Pros:
Smaller
Has trackpad (makes editing and selecting SO much easier)
Sense UI (+its features ie copy/paste in browser/messages)
More fluid
The ones with AMOLED display are definitely nicer
Rooted with ROMs available
WiFi connection more stable
Incredible Cons:
Switch from AMOLED to LCD
OK call quality (could do better)
Droid X Pros:
Bigger screen
Very nice call quality
Sturdy built
Really good battery life
Droid X Cons:
A tad too big (I think a perfect size would have been 4 inch screen)
Lags at times
Locked bootloader
Missing copy/paste in browser/messages (this is a big one for me)
Camera focus sucks (it unfocuses right before you snap the picture)
Both get really good reception - Tie
Both are on backorder now until August 3rd. - Tie here as well
I bought another Incredible and it should be here within a few days...I will run side by side comparisons...but at this point, I am very unsure.  X is just too big.  
