Note: what is natural/from evolution is not always good.
There is none, and there won't be any.
I learned from evolution that there can be no such country, not for many centuries at least.
Although humans are a species with high Male Parent Investment (MPI), it happened "recently" and males in evolutionary psychology are wired/supposed to go around and mate as often as possible. This may change over many many generations.
Women on the other hand can take care of a single child at a time.
Let us do the math:
50% of Joe's/Jane's genes who's born in 200,000 BC will go to his son and his daughter.
His daughter although prolific, spread Joe's genes to a handful of children.
While his son, assuming he was prolific, can theoretically have countless children because he can have many mates, see polygamy was the norm then.
That a Joe with brain wired to preferred educating and grooming sons and not his daughters to be of high status will have higher chances to spread his genes than a Joe who did the opposite.
Males at that time didn't have equal chance of mating as females. Females where in an advantagious position which in evolution forces parents to "care" more about their male offsprings, which translates in our conginitive brains today to "prefer male children".
Their offspring will subconsciously (hard wired) prefer male offspring too.
The bright side:
Seeing how the society is today in the developed nations, this tendency is supposed to diminish in just thousands of years. Given a selection pressure worked against Joes who prefer sons.
At the end
There will be no country that prefer females over males if things continues as they are today, but for sure the subconscious preference should disappear in the next 100,000 years.
Conscious preference should disappear much faster.
Countries that prefer a gender, is not the same as individuals preference.
Individuals with different socioeconomical status prefer (subconsciously) different genders in many societies.