IFWT is technically more superior for sure but like IFWT , FFKD has HEART. Both stories are more geared toward family and brothers especially are the main plot in both the shows and if I'm going to be honest, the male leads in both shows are so gorgeous. There's also a very essential crime plot even though IFWT crime aspect is more nuanced and FFKD is more dramatic melodrama. Both drama are total tear-jerkers.
Both have gorgeous male leads, both are melodrama tear-jerkers, both have crime and action plots that are pretty solid, dark, and satisfying. The only major difference is HJS is more about the romantic relationship, and FFKD has a very strong estranged brothers and family plot. Both can get pretty dark. But imo the fl in HJS might be a pushover, I never resented her because being submissive is not wrong. But the fl in FFKD has some seriously problematic manipulative behavior.