Asus is generally considered to be one of the best motherboard makers and it's personally the only kind i'll run. I've had bad experiences with a couple other kinds. I haven't used a Gigabyte, but i do hear good things about them (though maybe not quite as much as for Asus boards). So you're probably safe to go either route, though i'd probably get the M5A99FX PRO R2.0 out of those (i have a M5A99X EVO and it's a great board).