I think that how religious a girl makes no difference. What matters is how devoted to Torah she is. The idea of the sages of marrying a daughter of a Torah scholar to me means to marry a girl who is devoted to the idea that her husband and children should learn Torah at all cost. Religiosity has nothing to do with this. I can see that there are plenty of girls who are religious, but are not interested in her husband learning Torah. That does not count as a daughter of a true Torah scholar. [Sadly Torah has become a easy way to make a living. Girls with sense (but no fear of God) will marry these kinds of hypocrites. What really matters is the people who will stick with Torah at the cost of having no money