Salam Wanderer,
I don't believe the Quran (or Allah) values daughters / women over boys / men.
Both are a creation of Allah, and many verses attest to how both are equal under the "eyes" of Allah and how both will receive equal reward(s) for their acts. The Quran also makes it clear that that the only basis of superiority and excellence that there is, or can be, between us is that of moral excellence / righteousness:
"O mankind, indeed We have created you from male and female and made you peoples and tribes that you may know one another. Indeed, the most noble of you in the sight of Allah is the most righteous of you. Indeed, Allah is Knowing and Acquainted." [Quran 49:13]
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Now, with respect to those verses which supposedly seem to indicate that daughters are somehow less than sons it is vital to keep in mind the context / era in which those verses were released. The era / time of prophet Muhammad (pbuh) was one in which women were seen, by the pagan Arabs, as inferior (physically and mentally) and unequal to men and hence regarded them (their daughters) as a mere liability and their birth as a disgrace; therefore, those verses are obviously ironical and in a way rhetorical, as well.
Hope that clears it up