I'd say Asus! not because Im a fan or supporter of Asus or anything xD
More features, Japanese Solid capacitors, great for overclocking (if ur into it), the quality is great!
but I bought this wonderful motherboard called: Rampage II Extreme... and its awesome
(Rampage III Extreme is out though).
been using Asus motherboards for over 6 years, and never had any problems!
But I would also recommend Gigabyte, EVGA, DFI, Foxconn and Supermicro.
But I'd say that u shouldn't go for MSI, some friends of mine had many problems with their motherboards.