With HRA, you are guaranteed that your receiver is post-WWII. Some say HRA were a notch higher quality, perhaps because of the lack of wartime pressure. Anyway, the overwhelming majority of M1's have been rebuilt at some point in their service lives, so the chances of one being "better" than the other (for shooting purposes) is largely luck of the draw.
I have both a SA and HRA M1, both service grades, that I bought a few years back. Both appeared virtually unfired after rebuild, although of course CMP test fires them. Both were electropencil marked as rebuilt in the mid-60's. I have not noted a difference between the two, except the HRA came with a broken recoil spring.