As Robo says, UMC, "Union Metalic Cartridge", is a division of Remington as Western is for Winchester. Any of them as good as the other. The difference in factory ammo, small as it is, is largely in the bullets.
Fact is, Remington brass tends to be a tiny bit softer and thicker than Winchester-Western. Neither is "better", they are just a little different and it depends on what we want from it. Softer, thicker cases tend to last for more reloads while harder, thinner cases allow for more powder and tends to allow for a little more velocity. Most reloaders will never seem much difference.
How we size our cases and, to some extent, the tools we use for it, make more of a difference in how long our cases will last than the brand.