sapphire is amd's biggest gpu board partner and they make great video cards. but msi is a monster board partner too for both amd and nvidia and msi is agruably, along with gigabyte, the largest of the board partners for both nvidia and amd. evga is nvidias largest board partner. asus is also a board partner for nvidia and amd but not quite as big as msi or gigabyte.
msi makes great stuff, when it comes down to it, i would prefer a sapphire but i wouldn't pass on an msi card if im getting a good deal. it really depends on the card and its features. but honestly all the big 5 board partners are reliable and are large companies with no reason to put out a bad product.