... this coming from 2 people who have never used one.
The asus board is shite. Check out the forum for it as Asustek:
ASUSTeK Computer Inc.-Forum-
The board has a SLEW of problems which have yet to be addressed by Asus. The wifi does not work, plain and simple. Even with the latest bios 1002, its still not working for most users. RAID setup is very complicated, finicky, and just does not work properly. 1066 RAM support is terrible, and not many people can get it stable. CrossfireX is only working on this board for people running dual X2's, 3-way and 4-way setups are not working for the few who can afford to try. Crashing, Freezing, Lockups are common and an everyday occurence for me, and it drives me crazy. The BIOS has about 20 or so new options that have no explanations and nobody really knows what they do, we just speculate on the forum. Asus support has been NIL. And the crunching!! I have never had a louder motherboard. I thought it was my HDD's but its not, its the motherboard's power-switching circuits, they crunch nonstop with cpu activity, its enough to make your brain hurt. As if that wasn't bad enough, whenever you launch a 3D app you get a super-high pitch squeal that sounds like its definitely giving you cancer.
Having 4 pci slots seems cool at first until you realize they are so close to each other that you will never be able to use them unless you have single-slot cards and/or a multi-gpu watercooling setup with full-coverage blocks ($$$). The boards with 3 slots make much more sense and are way more useable.
The DFI board, on the other hand, I have heard nothing but good about. There were some issues at first but they have been fixed by bios updates (imagine that). If you really want the ASUS board, buy the DFI and I will trade you because I was duped by cool-looking copper heatsinks and useless pci slots.
Anyways, just thought you might want to hear from someone who is actually putting up with one every day before you buy.