Save Me keeps coming to mind.

It is a song with an emotional melody and a sophisticated beat that is appealing.
The poignant lyrics and chorus linger in your memory after just one listen.
The members' smooth vocals and rap blend naturally, making it even more polished.
The choreography is also beautiful, so you can feel an even deeper emotion if you watch the stage video as well.
It is a hidden gem by BTS that you fall in love with the more you listen to it.
If you like calm yet addictive songs, I highly recommend this.