I use gigabyte, built 3 computers with gigabyte z77 boards and I like them. I havnt had ASUS in 5 years, the last ASUS I had the LAN went out and the voltage would not go over 1.85 volts so I could not adjust the voltage for the higher speed of the RAM, well I settled for less speed. The product description did't say it would not go over 1.85 volts though.
Like anything, some people like nividia, some people like ATI, some people like Apple products, some people don't like Apple products.
ASUS is a good product, they make nice boards. I have a ASUS monitor and I really like it.
Asrock, I looked at the extreme 4 or 6 and I can't remember now. There was some good reviews out and looked like a nice board
Now the Intel z68 series Gigabyte board, from the percentage of people having problems ( i read on newegg forum and looked into on google) with a start-up loop with the OS. I think I would avoid that series like the plague.
Go pick out your ASUS MB.....coming in this forum your just going to get varied opinions, because of someones bad experience or because they just don't like it or because somebody else didn't like it so they don't like it.
Good Luck on your build.