sky gardens is a legit housing scheme but location is more like a resort away from population. I have personally visited the location, you have to cross mountains to reach this area
Bahria Golf city is giving the right sense to this area as it is not a housing society, it is for spending vacations. So, sky gardens doesn't get good response for residence.
Gulberg, on the other hand, is a good place for living in main city. Better visit these locations so that you can have clear understanding of pros & cons of these places.