In case of the SE535 many will argue that different might be better, though. As in more neutral, less fatiguing and better extension. (I will also claim some universals have better resolution, but I will have a hard time to prove that as it is only based from my memory when I did a big comparison with other IEMs.)
But I've seen in another thread that Spyro does not like to discuss that topic or has a different perception, so in his case, the SE535 is really the best.
Still depends on one's criteria for what "great sound" is to THEM which can take a long time to figure out. Sure, you can cherry-pick certain characteristics (like resolution) and say X is better than Y but what about the whole package? For example most would agree ER4S has terrific treble. But many of those same people would say it doesn't matter because the weak bass is a dealbreaker.