(For the purpose of this post I am excluding over 40, i.e. trot, from the equation.)
This year's gallup has 4 balladists (including 1 trottist) , IU, Lim Youngwoong (considered a trottist, but he began as a balladist and his trot is often indistinguishable from ballads which is why he is more tolerable to the younger Koreans and even some i-fans), Lee Mujin and Akmu.
The most popular songs of 2021 include
Lilac (Lee Jieun)
Traffic Light (Lee Mujin)
Nakka (Akmu)
Foolish Love (MSG Wannabe)
and, incredibly,
Through the Night (Lee Jieun), a 2017 Song!
(Some of them have faster tempos, but they are considered to be ballads. I thought about including Taeyeon's Weekend, which could be called as ballads to some ears, but decided not to.)
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Although BTS has dominated the world, its fame is because of its world domination, and if left to the K-O-R-E-A-N-S the balladists will return and take over Kpop again.