Ever since they topped the 1970 MGM auction, the ruby slippers are THE prop that all others are measured by. They say the next pair that goes to auction could bring $1.5-$3 million. The last pair that sold (many years ago) went for $660,000+. The witch hat went for less than half of that last year.
The witch hat may be iconic to prop collectors, but to little girls? Most little girls (including mine) go through a "Dorothy" phase at about 2-4 years, wanting their own dress and ruby slippers. I don't know of one that wanted to be the witch, except perhaps at Halloween, (even then, I don't recall knowing one personally). "A" witch, maybe, but specifically the OZ witch?
I used to attend the Wizard of Oz fest in Indiana every year, and 99% of the little girls in attendance were absolutely TERRIFIED by the witch (as was mine), and there must have been 500-750 little Dorothys showing up every year.
The witches' hat is a great (even iconic) prop for sure, but nothing stands up to those ruby slippers.