I voted for Kide and ddickky's "StarWish" and Kira's "Fighter"!
"StarWish" is just so lovable and touching, the tuning is also great! And so does
her voice provider's cover, she's so amazing I love her!
As for "Fighter", I always love Kira's top-tier tuning and great pop-sounding music. We want more like him!
As for the unmentioned demos, I immediately thinking about this remix of 2AM's "Never Let You Go".
This cover of Signal's "Cendrillon" is also great!
Also apol and Empath's "NeapolitaN"
rerulili's "Boku ga Monster ni Natta Hi" is also my fav!
I also love zzz's "Elixir", the tuning is somewhat simple yet still sounding great, eventhough this song become "a mainstream Korean demo song"
Talking about simple tuning, Yes, Peperon's tuning method is still considered simple yet good sounding and popular among the community, but his music is also great! I also favorited "Fragments of the Night" as well as this underrated song.