I agree that there is no "overall" strength difference in any of the "currently" available axles. They all are limited by the size of the splined shaft.
I recommend GCK HD axles for replacements for broken stock units because the price is good (~$125) and they carry a lifetime warranty.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.