I personally like Gigabyte the best, their motherboards are very high quality and have so many features.
I have 2 computers that I built, both with gigabyte motherboards
I currently have a DFI LanParty PRO 875 and I am in love with the DFI boards. There are a ton of options and also a ton neat little stiff that comes with and on the boards (IE carrying case for the computer and UV reactive compenents). I have heard good things about other boards but I think that I am going to stick with my DFI!
I like ASUS boards, they are very well built.
I like the bits and pieces you get with the package too, there is nothing worse than spending hundreds on a motherboard and getting no knick knacks in the package :p