i agree with rolli. Both boards have just about the same specs. Any major differences might just be with the software or what they support (ie. Asus had the ROG connect feature) but other than that its what you prefer.
I personally like Asus over Giggy. I like their quality and performance - never failed me =)
You are comparing two radically different MOBOs in two different price points.
Clearly, the ASUS Crosshair IV Formula is better and might be overkill unless you want to run a high OC. Next, I don't like what Gigabyte has been building lately their mid-range is built more like ASUS low-range boards when it comes to power.
Here are (3) that I would consider and I would recomend that you carefully review for your specific needs. All support CF, RAID, up to 6-Core AMD, the M4A79T Deluxe lacks USB3/SATA3 but offers 3/4 WAY CF, the other two do offer USB3/SATA3.
However, the $50 saving for the ASUS M4A89TD PRO/USB3 is something to take note and is a great AM3 MOBO.