Keep in my mind that this is all my opinion, and no, I'm not using the term some of you are thinking of.
Minimum of 2.4M Genie ULs
Minimum of 5M Melon ULs
Minimum of 2.5M downloads
Minimum of 100M streams
Appeared on year-end Gallup survey at least once
Charted for at least a year (52 weeks) in the top 100 of Gaon
With that in mind, here are the 10 songs that hit at least 5 out 6 criteria:
BTS - Spring Day (6/6)
BTS - Boy with Luv (6/6)
TWICE - Cheer Up (6/6)
BTS - DNA (6/6)
BTS - IDOL (6/6)
Red Velvet - Red Flavor (6/6)
iKon - Love Scenario (5/6, no Gallup)
TWICE - Dance the Night Away (5/6, no Gallup)
BLACKPINK - AIIYL (5/6, no Gallup)
BLACKPINK - Ddu-Du Ddu-Du (5/6, < 1 year on Gaon)