Depends on the voice actors.
If (one of?) the male PC voice actor(s?) is someone whose voice just clicks with me and the male default face is decent / it's relatively painless to make a decent looking male PC (yes yes, I'm shallow), I'm gonna mostly play with a male PC. If (one of?) the female PC voice actor(s?) is someone whose voice just clicks with me, and the female default face is decent / it's relatively painless to make a decent looking female PC (again, shallow), I'm gonna mostly play with a female PC. If the CC / default faces are absolutely horrible, I'll go with the gender whose voice I like best with the condition that his/her face doesn't look too much like it was introduced to too many blunt objects at a young age (my relationship with CC has been somewhat difficult in the past).
If both are kinda meh or I don't have strong feelings about either, I'm gonna play as a female first and as a male later.
If I really don't like / don't click with the(/any?) female/male PC voice actor(s?), I'll just play as the opposite gender for the majority of the time and maybe do one female/male playthrough just for certain romance (or out of obligation).