No particular fields. I knew a really nice and smart professor primarily working in logic who spent a while wasting time on some philosophy of language, many tedious and reinterpretations of modern philosophers (your Mills and Sartres etc., but also more obscure figures I can't remember the names of), a rather arrogant philosopher of economics who was doing things like taking models and assume they were intended as true descriptions of reality, and much more. There were still probably more people doing at least somewhat interesting and good work in the department than not, but when reading papers you'd find just so much that adds little value. As for students, the average level of ability was low.

I have a substantial amount of disrespect for metaphysics, but I don't think the philosophers in that field were better or worse than average, I just think the field itself is largely wrongheaded.