Their chorus is very catchy and that it like stuck in your head for awhile and memorable which is why they easily get tons of international fans. Bp, 2Ne1 and Big Bang are the obvious one as they're the most popular in the company. Same goes to most of their solo songs. (Eyes, Nose, Lips) from Taeyang and Jennie Solo are one of my favorite. Even song that I didn't like from them like Ice cream, I still cannot get rid the post chorus and chorus part and even silently sing to it even I don't like the whole song.
As for their new group, Treasure I don't know if it still like that as I never heard their songs.