Sometimes one has to make a choice between two individuals who wish to lead the prayers (be Shaliyah Sibbur). One comes from an important family of fine pedigree but he himself is not so righteous, whereas the other comes from an inappropriate family, but he himself is very pious. Which of the two should one choose?
The Taz says in the name of the Rosh that the praiseworthiness of the Shaliyah Sibbur does not come from the family. Even if he comes from an unworthy family, but he himself is a worthy and righteous individual, he should be chosen over someone who comes from an important family but is, himself, unworthy.
It goes without saying, however, that if the two are on an equal level, that the one from the important family should be selected in preference to the one from the unworthy family, since the prayer of one who is righteous and the son of one who is righteous (Saddiq Ben Saddiq) is preferred.
(See Shebet Mussar, Ch. 34, Oth 2)
