Zico is one of my favorite artists; he’s so talented when it comes to composing music and lyrics. Some artists/songs that I would suggest are:
Crucial Star (크루셜 스타)
FatDoo (팻두) - Phone Call With A Dead Friend (죽은 친구와의 전화) (Feat. Heenain)
Just Music (저스트뮤직) [Make-up of a group of artists]
SOOL J (술제이)
Simon Dominic (사이먼 도미닉) [He has a very deep and unique voice]
I hope this was useful!