Here are my personal favorites:
SF9 - Good Guy
Before this I've only been casually checking out their title tracks. I liked O Sole Mio, and like everybody else I jammed to Now Or Never, but it wasn't until Good Guy (and seeing them cry during their first wins) that I learned all the members' names, listened to their entire discography, watched a ton of their videos, and even went all the way back to watching the survival show which formed the group. I'm in this deep, you guys.
NCT 127 - Love Song
Their latest title track Kick It is fine as a hype song, but it's the mid-tempo R&B b-sides in the album that shine for me. This one is my favorite (the harmonies! the adlibs!). Others I enjoy include Elevator, Boom, and Pandora's Box.
Vincent Blue - LTNS (feat. Verbal Jint)
I got hooked on his smooth voice late last year and he released his first mini album just last week. Is this what they call bossa nova? I'm bad with genres.
Source: FNCEnt, NCT 127, 1theK