I do not believe Ms. Coulter was more qualified than Miers, and I don't think she ever wrote that either - didn't Coulter say something like "Miers is qualified to be on the SCOTUS like I am qualified to be a sumo wrestler"?
Not an exact quote, but Ann stated or wrote that she had better qualifications (academic and professional) than Miers and that she (Ann) was still not qualified to be a Supreme Court justice.