Thank heavens it’s no longer the case (if it ever was) that tough graders map almost perfectly on to the great teachers. That really sounds like a masochistic fantasy of the University of Chicago of yore: if it isn’t painful, it can’t be valuable, because if we were learning without pain we would be just like everyone else. For what it’s worth, my experience at other institutions was that the two qualities were completely uncorrelated.
As a practical matter, if you want extensive feedback on your work from a full professor, go to a small liberal arts college, where that’s what they are paid to do. Otherwise, at a university like Chicago, you are going to get detailed feedback from graduate-student TAs, or in Core classes in some cases from recent PhDs hired as non-tenure-track Core professors. That’s really not a bad deal. Chicago (like its peers) has fabulous graduate students in most departments, and they can do a great job of mediating between the undergraduates they still remember being themselves and the faculty with whom they work 24-7 as indentured servants. The Core faculty positions are great jobs for people who are often great scholars but for one reason or another do not yet have a tenure track offer (or do not have one they can accept and keep their marriage together).
For both of my kids, some of their most productive learning relationships at Chicago were with graduate student TAs, including their first-year writing instructors and in one case a BA thesis preceptor. My wife and I both had similar experiences four decades ago at Yale. A number of our grad-student TAs grew up to be pretty distinguished people, by the way. I had future English Department chairs at Harvard and Yale, a federal appellate judge on the short list for the first Trump Supreme Court appointment, and a future chair of German Literature at Michigan. My wife had a respected historian and a seminal feminist legal scholar who was then in the process of writing the book that made her famous.
At Chicago, one of my kids (in a relatively small department) had extensive formal and informal relationships with full professors and tenure-track junior faculty, including real feedback from them, but the other (in a larger department) really didn’t. Some of that was just bad luck. The person she wanted as a BA thesis supervisor had a sabbatical planned for her 4th year, the next choice took sudden leave when she had a chance to adopt a baby, someone else got seriously ill, and she wound up with an administrator who hadn’t done scholarship in 20 years and came into the picture months late. Some was department style. My son’s department did a ton to integrate undergraduates into the life of the department. Its senior faculty really enjoyed teaching undergraduates in small groups. I have related many times how one of the best-known professors in the department, having taught a 10-person seminar for fourth-year majors fall quarter, kept the seminar going through winter quarter on a voluntary, no-credit basis. (Something that not only deepened my son’s understanding of his field, but also deepened his friendship with one of the other students in the class, with whom he is now married.) Anyone who wanted could get involved in faculty research. My daughter’s department – one of the highest ranked in the university – just wasn’t like that.