Depends on your uses. The MSI has more features, but you shouldn't buy the board unless you know you need three PCI-e slots or any other feature the board has.
The AsRock has PCI slots (while the MSI doesn't) so if you need a PCI slot then get the AsRock.
Basically, unless you know why you're paying more for the MSI board then don't buy it.
If I were you I would get either the ASUS P8Z77-V
or the Asus P8Z77-V LK
. Again the more expensive board has more features and will be better for overclocking, but only get the more expensive one if you know you will need the extra features.