Athletics, academic rigor, prestige of faculty, quality of resources, access to labs and research opportunities - all of these things and more have an influence on how we gauge the quality of a university. On some level though, all of these factors are determined by a university's finances. Wealthy schools like Harvard can pay for top notch facilities, which attracts the best professors, which in turn brings in the most talented students. With this in mind, there is some basis for dividing the universities into tiers on the basis of their finances. We could simply rank colleges by per capita spending or per capita endowment, but I think that it is much better to look at how a college gets its funding, rather than what that actual funding is. A university that funds itself through alumni donations has fundamentally different goals than a university that gets it's funding through stockholders. I think that there are four distinct tiers:

Tier 1: Most money comes from endowment and grants. Tuition supplements this funding. Universities in this tier tend to be need blind, and are able to admit students exclusively on the basis of merit and are highly generous with financial aid.

Tier 2: Endowment and grants pay for improvements, but the bulk of costs are paid for by tuition. I think that this includes most good private universities and public universities that get supplemental funding from their state governments.

Tier 3: Tuition pays for nearly all costs. This is mostly lower tier private universities. These schools are probably overpriced because they need to dip into tuition to fund improvements and expansion.

Tier 4: The for-profits. Shareholders invest money in the university's holding company's stock and that money pays for improvements, development, and marketing. Oh God, the marketing! The University of Phoenix, one of the largest for profits, spends hundreds of millions of dollars in advertising and even owns its own professional sports stadium. Tuition is used to fund the school's operations and pay back the shareholders. While these schools charge tuition that is totally out of line with what they offer, much of their funding actually comes from federal loan programs bailing out the graduates who have no ability to pay back their outrageous "college" loans.