There are many considerations beyond size and sex. One of the most important aspects of choosing a dog is finding the best breeder you can. It appears the OP is doing this and doesn't need additional information, but for those that may be reading here are some additional thoughts. Hopefully someone else looking for a responsible breeder will benefit from the info.
Every breed is susceptible to certain health conditions. I know that Neos, like Boxers, have a high incidence of DCM (Dilated Cardiomyopathy), as well as eye/hip/thyroid/elbow issues. Not to mention temperament issues. It's NOT all in "how they're raised." Genetics plays a huge part in temperament. Bloat and torsion, GDV, is another concern with the breed. It has fairly recently been determined that there is a genetic component to bloat. Losing a dog to GDV is devastating and it would be good to know if other dogs in the line had bloated so extra caution could be taken with the pup. One more I always suggest is the test for Degenerative Myelopathy (DM). It's relatively recent test, but will reliably determine if the dogs being bred are carriers of the gene for DM. DM is inherited in a recessive manner, so the offspring must receive two mutated genes for them to develop the disease. DM is also devastating and definitely worth testing for in parents. It's very similar to ALS in humans. That being said, I'm not sure of the incidence in Neos, but it's a huge issue in boxers and I've known English Mastiffs that have had it as well. In addition to other eye isses, cherry eye is thought to have a genetic component. Thyroid issues are also a concern.
This is a list taken from a generic kind of page (
https://www.gooddog.com/breeds/neapolitan-mastiff/health-testing-guide ), but it's concise and has good explanations of the tests. A vet check isn't enough.
"A breeding program following "Excellent" health testing will report to screening their dogs for:
Cardiac Evaluation (registered with OFA) - Cardiac Evaluation (registered with OFA) is useful in screening dogs for congenital heart conditions that can be passed down to the puppies. Congenital heart conditions are malformations of the heart, valves, or major blood vessels. The exact mode of transmission, or inheritance, is often unknown but it is recommended that breeding dogs are screened prior to breeding. The type and frequency of the screening examination performed varies by breed.
Elbow Dysplasia Finals (OFA, BVA, SV, FCI) - Elbow Dysplasia Finals (OFA, BVA, SV, FCI) is a complex condition involving both genetic and environmental factors that can cause varying degrees of pain and loss of function in the affected joint. No genetic test is available to date, therefore, the recommended screening test is x-rays. Definitive reports include OFA radiographs taken after 2 years of age or another recognized screening and grading program (e.g. BVA, SV, FCI) following the validated process and minimum age for that organization.
Eye Certification (CAER, registered with OFA) - Eye Certification (CAER, registered with OFA) screens dogs for the presence of heritable eye disease. Most eye disease is thought to be genetic but the specifics of many diseases have not been identified to date. Screening of breeding dogs decreases the risk of heritable eye disease being transmitted to puppies. Breeding dogs should have annual eye examinations as onset of symptoms will vary by disease and individual.
Hip Dysplasia Finals (OFA, PennHIP, BVA, SV, FCI) - Hip Dysplasia Finals (OFA, PennHIP, BVA, SV, FCI) is a complex condition involving both genetic and environmental factors that can cause varying degrees of pain and loss of function in the affected joint. No genetic test is available to date, therefore, the recommended screening test is x-rays. Definitive reports include OFA radiographs taken after 2 years of age or another recognized screening and grading program (e.g. PennHIP, BVA, SV, FCI) following the validated process and minimum age for that organization."