It depends if you are going for SLI or CrossFire i would recommend the msi because it can run at PCI-Express 3.0 X16 op tho 3 GPU and it has no fan and the fans on motherbords are most of the time loud.
The asrock only supports 1 PCI-Express 3.0 X16 otherwise they run at x8.
But they are both vary good.