>jpm
-The last (third long) pci-e slot. On Asus if one wants to set it to 4x mode he has to switch off e-sata, some usb ports and pci-e x1 AFAIR. No such restrictions in Asrock's case.
-Asus had a little advantage in P67 concerning usb3 compatibility (Nec chip). But it is no longer valid as they changed usb3 controller in Z68.
-USB3 front panel as a bundle in Asrock.
-surprisingly robust community of Asrock users and faster response with bios updates from their support team.