I’d agree on Equal Rites; Sourcery is a _weird_ Discworld book, though I think it’s the one that most blatantly hits the theme, which shows up more subtly elsewhere, that “great men (TM)” are _a bad thing_.
He must have liked it; he rewrote it later as Good Omens.
I find it hard to see Good Omens as a do-over of Sourcery, but I guess they do have something in common.