if the Asus is the cheapest in your region, then there is no reason not to get it. +1 to david cassar's comment and reasoning. The gigabyte model is also good quality and are also renowned for their quality and customer support. You cant go wrong with either.
the galaxy gtx 660 gc is 180 dollars in amazon but aren't as well known as asus. Go with the asus because asus as i said before is a quality brand and since it is the cheapest.