Disagree. Mary was a vessel.
Was she favored? Yes. But I would ague that she was special because she was chosen - not chosen because she was special.
Going back through the lineage of Christ, you find adulterers (David) & prostitutes (Rahab).
To his own glory God chooses & uses who he will - despite deep character flaws.
As for Mary - was she rare? Probably. Was she unique in terms of her purity? Probably not.
Just mho...
As a traditional Roman Catholic I believe what I posted.