When I personally consider this idea, I envision these rankings not to be something that uses metrics that are still tied to the parts of the system that gave us pause in the first place; e.g. average salary, number of graduates working in their field, etc. I prefer to promote the concept that life is not a straight line and that success is not solely measured by making one plan before university and sticking with it.
That being said, what I see these rankings being is a metric based on the impact on the community (local or global) in different categories. For example, such and such university has x amount of graduates who have worked in their community and created programs to combat homelessness, or lowered the percentage of the population that is homeless. This would give the university a higher score in the 'social responsibility' category.
I also find this idea interesting because to me it leans away from education being a commodity and makes one ask what other value we gain from it.