Just to be clear you are talking about academic qualifications of students at the point they are applying to college? All colleges value academic preparation, similar to how they value the academic experience that each has designed and offers to their matriculants.
To help you understand what colleges value, perhaps start with their mission statements? Best to go right to the source…where each school is literally telling you who they are and what they value.
There is some variability among these mission statements. Not many highly rejective schools (I assume that’s the small subset of schools you are mostly concerned with) state they are limiting their mission to educating only the ‘best’ academic performers (however one might define that.) Some mission statements directly state the desire for a diverse student body and community.
Our mission to educate future leaders is woven throughout the Harvard College experience, inspiring every member of our community to strive toward a more just, fair, and promising world. The mission of Harvard College is to educate the citizens and citizen-leaders for our society.
Princeton University advances learning through scholarship, research, and teaching of unsurpassed quality, with an emphasis on undergraduate and doctoral education that is distinctive among the world’s great universities, and with a pervasive commitment to serve the nation and the world.
Dartmouth educates the most promising students and prepares them for a lifetime of learning and of responsible leadership through a faculty dedicated to teaching and the creation of knowledge.
Columbia University is one of the world’s most important centers of research and at the same time a distinctive and distinguished learning environment for undergraduates and graduate students in many scholarly and professional fields. The University recognizes the importance of its location in New York City and seeks to link its research and teaching to the vast resources of a great metropolis. It seeks to attract a diverse and international faculty, staff, and student body, to support research and teaching on global issues, and to create academic relationships with many countries and regions. It expects all areas of the University to advance knowledge and learning at the highest level and to convey the products of its efforts to the world.
Cornell’s mission is to discover, preserve and disseminate knowledge, to educate the next generation of global citizens, and to promote a culture of broad inquiry throughout and beyond the Cornell community. Cornell also aims, through public service, to enhance the lives and livelihoods of students, the people of New York and others around the world.
Northwestern is committed to excellent teaching, innovative research and the personal and intellectual growth of its students in a diverse academic community.
Established in 1789 in the spirit of the new republic, the university was founded on the principle that serious and sustained discourse among people of different faiths, cultures, and beliefs promotes intellectual, ethical and spiritual understanding. We embody this principle in the diversity of our students, faculty and staff, our commitment to justice and the common good, our intellectual openness and our international character. An academic community dedicated to creating and communicating knowledge, Georgetown provides excellent undergraduate, graduate and professional education in the Jesuit tradition for the glory of God and the well-being of humankind. Georgetown educates women and men to be reflective lifelong learners, to be responsible and active participants in civic life and to live generously in service to others.
Yale is committed to improving the world today and for future generations through outstanding research and scholarship, education, preservation, and practice. Yale educates aspiring leaders worldwide who serve all sectors of society. We carry out this mission through the free exchange of ideas in an ethical, interdependent, and diverse community of faculty, staff, students, and alumni.
The mission of Brown University is to serve the community, the nation, and the world by discovering, communicating, and preserving knowledge and understanding in a spirit of free inquiry, and by educating and preparing students to discharge the offices of life with usefulness and reputation.
I especially like how Bowdoin addresses choosing students with ‘varied gifts’:
It is the mission of the College to engage students of uncommon promise in an intense full-time education of their minds, exploration of their creative faculties, and development of their social and leadership abilities in a four-year course of study and residence that concludes with a baccalaureate degree in the liberal arts. At the root of this mission is selection. First, and regardless of their wealth, Bowdoin selects students of varied gifts; diverse social, geographic, and racial backgrounds; and exceptional qualities of mind and character. Developed in association with one another, these gifts will enable them to become leaders in many fields of endeavor.
Lastly, this quote from Williams college, found on their mission page, directly answers your question that started this thread:
Diversity is not an end in itself, but a principle flowing from the conviction that encountering differences is at the heart of the educational enterprise—differences, certainly, of ideas and beliefs, but also differences of perspectives rooted in the varied histories students bring with them.