I'd go for ASUS for reliability, overclocking, and trust.
8gB of ram is enough in most cases but you'll be the judge of that
8 channel means 7.1 if I am right but do you really need that.
Amd motherboard don't current have a PCIe 3.0 slot but all the current graphics cards works fine on a PCIe x16 2.0 slot.
Generally all audio devices are same but I think I've seen some motherboards with better onboard audio devices. Board with good audio adapter http://www.newegg.com/Product/Product.aspx?Item=N82E168...