The Dingjia Wuwang Divine Fist may not be well-known outside, but within the Xuanmen itself, it carries significant renown. If we were to rank fist techniques based on the Xuanmen's criteria of "the top three before the Golden Core realm" and "the top three after the Golden Core realm," the Dingjia Wuwang Divine Fist could certainly contend for a spot among the top three fists in the post-Golden Core, no, even after the Nascent Soul realm.
As for the Immortal Palace's Heaven-Breaking Divine Force Fist, it is unquestionably the top technique across all cultivation realms. Well, it's basically a force-based fist. Back in the day, the Immortal Lord didn't have much else going for him, but his single mastery — punching through the heavens — remains formidable even now. The principle is simple: the more iron you pound, the more output you get. Pound iron infinitely, and your output becomes infinite. You tell me, isn't that strong?