Comparing The Downward Spiral to The Fragile is like comparing Dark Side of the Moon to The Wall (Pink Floyd). While both of these Floyd albums are classics, they are both different, and people like them for different reasons...DSotM is like TDS in that it is simpler to understand. DSotM is life from birth to death, and TDS is just a guy pealing away the layers until he's at the core of himeself. TW is about a guys life and the problems he went through as a child and all the times he has failed to overcome his depression, and TF is about a guy who is already at the core of his depression and his multiple failed attempts to over come his depression, until finally realizing what reality really is and who he has become...brig left in a place worse than where he started.
The Fragile is deeper and more complex to understand the first time, unlike The Downward Spiral, which is relatively simple to understand.
I personally like The Fragile more that The Downward Spiral...because its a better album that he more meaning than the other.