I've also used gigabyte for my first custom build , I really put a well thought in it and , Asus just never looked interesting , cause many mainstream pc manufacturers use asus , a lot of asus products are well redesigned OEMs , I won't say this for motherboards , they have some of the top tier , but it's just for my needs that I felt gigabyte to be more of a good choice , looking at dualbios which saved my whole mobo from RMA. And Award bios is much better than AMI(features) , or whatever asus uses.
To add too it , it has been reported asus mobos have their chips much more hotter and the heat is much more spread on the large portion of the motherboard , plus , the asus EPU chip , is a lie.
not to mention a shipload of complaint threads in their forums about problems and failures of asus mobos