1. Depending on the strain the male used in a cross can make a real difference. An example would be the original White Widow, that was renamed Black Widow. If using it in a cross it is best to use the male White Widow/Black Widow rather than a female. The male passes on the most desired traits in a cross than the female does.
2. If you want to make good or high quality crosses, do not use crap genetics from Nirvana. Their line is mostly knockoffs and F2s, sometimes renamed so they can claim them to be their own creation. They have next to no quality control on their seed production so you can never be sure of what you will receive. Nirvana is the AOL of seed companies. Just like how AOL attracts people who are new to the internet and who do not know there are far better options available, Nirvana attracts people who are new to growing and who do not know there are far better options available.
The Nirvana customers here will scream bloody murder over that, but that is because they will feel insulted, they will feel their intelligence was brought into question due to their picking, and possibly sticking with, Nirvana. The typical Nirvana customer will eat a yard of their own shit before they will admit that they chose low grade genetics. Nevertheless, low grade is precisely what Nirvana genetics are.
If you want a quality cross, start with quality genetics. Even then the average grower will almost never end up with the best that can be found from a cross due to limitations of money, limitations of space and limitations of knowledge. They will not be able to grow enough plants, both male and female, to pick the very best phenotypes to then use to cross them with the plants of the opposite sex in every possible combination. A skilled professional breeder can begin with 500, 1000 or more plants only to cull them down to 50 or 20 males and females to then make every possible crossing combination with so they can find the best of the best. Even then at times they are not successful in finding anything truly special. It can take years and years working with the same breeding stock for a skilled breeder to find the right cross, one that is worthy to be marketed.
True breeding is much, much more than chucking pollen and making seeds.