When I think of difficult choreo I tend to think fast rather than complex bc that’s more common in Kpop so things like black on black by nct that have a lot of foot work or that vibrating thing that shownu is way too good at in Shoot Out. I think Blood Sweat & Tears is a pretty good example of a dance that is just over all complicated tho.
I can't speak from a dancer's perspective because I am not but I think the majority of them would be hard for us. If I have to name a few groups I'd say NCT and ATEEZ have some quite hard choreos probably...