To me it is Fantasyland. Fantasyland in DL is my second favorite themed area anywhere (behind only DL's New Orleans Square). The WDW Fantasyland feels so cheap and tacky in comparasion.
DL's Fantasyland has the following things WDW's Fantasyland lacks:
Awesome Facades on all the dark rides.
More and better dark rides. (3 more dark rides for me since I don't like Pooh, and Alice and Toad are my two favorite Fantasyland dark rides and MK lacks them completely. Plus, Pan is better in DL as it has small drops and the wonderful star field scene)
An awesome facade on Small World.
All of the above things really make the Fantasyland experience at DL so great.