"If it were my money, I would take the ASUS P8P67 Pro over the Gigabyte P67A-UD4. With the ASUS board, you are getting a detailed UEFI, an awesome auto-overclocking tool, better energy saving features, a USB 3.0 bracket , more SATA 6 Gb/s ports, Intel gigabit Ethernet, and in my case, scope for a better overclock. The Gigabyte board is essentially expensive for what is on offer, in terms of usability, features, and extras."
"The ASRock board has power/reset buttons on the board, a Debug LED, that USB 3.0 bracket which will hold an SSD (worth in my option about $15), and is almost $40 cheaper. The ASUS board is the slightly better performing, overclocking is easier on the ASUS, the ASUS has a longer warranty, the UEFI is slightly better on the ASUS, the ASUS uses Intel Ethernet rather than Realtek, but the ASRock will take socket 775 coolers. It is up to you to judge, but in my opinion, I would take the Extreme4, pocket the $40 difference, and invest it in something else for a PC build."
With that said, personally, if I'd have the money, I'd get the UD4.