Assuming you mean standard rifle & pistol die sets, I have tested many sets and found that, on average, there is no detectable difference in the ammo made from any dies, based on brand. So, devoted personal opinions aside, all of our 7/8"-14 dies are made to SAAMI standards, no more, no less.
That said, there are indeed "differences" in features between different brands/designs but which feature the user values most varies with the individual.