Godol is a relative term; it means someone who stands out among his generation in greatness, which is measured in terms of Torah knowledge, and righteousness. There is no measurable threshold beyond which you are categorically a “godol”, like there is when a person gets a medical degree and becomes a “doctor.” Being that the term is relative, different people apply it to different levels for people, and even among those who are commonly referred to as Gedolim, they are not all the same. Rav Shach was a Godol, but he was not the Chazon Ish, for example.
There seems to be a common misconception that we are unable to comparatively assess the level of various Gedolim. This sometimes leads to comments, like, well my group has their own Gedolim so we are equal.
We can compare “levels” – in fact, we need to in order to judge who is an authority in the first place! If you can’t compare levels then how are you to know that someone is a godol? The fact that he is “accepted” as a godol only means that many people have judged his “level” to be that of a godol. But if you cannot compare levels, then these people have no right to accept him as a godol in the first place.
And the same common sense that tells you so-and-so stands out among his peers making him an authority, tells you that certain so-and-so’s stand out even more.
Or less.
Part of knowing who to follow is to know who is greater. Godol mimenu b’chochma ubaminyan is an assessment that it legitimately made. And as Rav Shach writes – if you don’t know who to follow, follow whoever is greater – and, he adds, you can of course tell who is greater.
If you yourself don’t know, then that’s fine – not everyone can know the answer to all questions they encounter – but why in the world would you say nobody else can know?
And it’s an error in logic, too, because they themselves compared “levels” of other people! i.e.: “Rav Ovadia Yosef is the leading Sefardi posek of our times.” And how would they know this if you cannot compare him to other sefardi poskim?
And how can one know whether “any of us are on the madreiga of assessing the ‘levels’ of other people” unless you assessed the levels of all those other people who said arent “on the “madgreigah” to do that?
If i were to ask you who is greater – Rav Ovadiah or Rabi Avika — would you say you cannot compare people? Rav Ovadiah or the Rambam? Avraham Avinu?
So clearly, we can compare “levels”, its just that to some, certain comparisons are “obvious” and others are not. Well, to other people, perhaps who are more knowledgeable and skilled in assessing these kinds of values, other comparisons are also obvious.