Another consideration is size, males tending to be larger.

I currently have 3 female Labs, one of which is pregnant. I've owned Labs for almost 50 years, always females. I enjoy developing blood lines and breeding for hunters. I used to hunt a lot out of a canoe.. Did not want a hundred pound male jumping out/in the boat and so preferred smaller females.
I typically don't hunt very big water (EX: lower Columbia River) and so don't feel the need for the most powerful expression of the breed. I currently hunt most often with this female, #66 very agile, very fast.

[Linked Image]gas close to me