Honestly, I'd go with Michelle McCool. Most Women's Champions that happened since I've started watching keep me interested in some form to watch them, she bores me so much that I've actually forgotten that the belt still is being used. She's awful.
Candice Michelle was actually a good wrestler durning her reign. While she sucked for some point before, she started improving and by the time she won the belt she could actually pull off really good matches. Of course, she got injured (mutliple times if I'm correctly remember) and when she returned, her improvement seemed to be left on the shelf, so she left us with the impression we initially had of her, a bad wrestler and intended as eye candy. Quite a shame, acutally. Who knows how good she could of gotten if she never got injured.