They are both good quality motherboards. At this quality (and reputation) level you may see a very small percentage of returns, but not out of the ordinary.
The MSI is ATX and has a slightly better memory specs (at OC), and describes components as 'military specs'. Maybe they did a better job of describing their product. But ATX boards as you are well aware of, are slightly larger; more space, slightly better cooling.
So, my vote goes for the MSI!http://www.newegg.com/Product/Product.aspx?Item=N82E16813130275&cm_re=msi_870a-g54_am3-_-13-130-275-_-Producthttp://www.newegg.com/Product/Product.aspx?Item=N82E16813128439&Tpk=GA-880GM-UD2H
Good luck to you!