Personally I think it is Seventeen. Even now when the group still actively promoted and on the top perhaps only behind Bts in kpop now, many still forget they exist or know their impact. They lack of hit songs especially to gp. Kpop stan probably now one or two of their song and argue they have released hit songs but especially to gp and as their non fans I can't recall any of their songs when I can do that to any other top boy group.
Secondly, Nct except probably Nct dream if SM promoting them correctly. Other than that, I don't know if non fans will care because their system already confusing to many. And probably it's the only reason in the future make people talk about them.
So far, I think most top gg right now doing great for their legacy in the future.