My choice would be the Asrock. If you put a large(ish) graphic card in the GB board, you'll cover 2 of your SATA II ports. The AR board has 2 chassis fan headers for monitoring and letting the BIOS control a front and rear fan. The GB, only one. And the GB only has a 4 pin CPU power header if you're into O/Cing. (not a major drawback, but something to think about)
Plus the AR looks better IMHO.