Well these are some groups and my favorite songs from each one:
Super Junior- It's you, Marry U, Happiness
Teen top- Crazy, Fall in love
SHINee- Love like oxygen,
B2ST/Beast- Fiction, Beautiful night
NU'EST- Not over you, Action
T-ARA- Day by Day, Roly poly
2NE1- I love you, Can't Nobody
SS501- A song calling for you, Love ya
f(x)-Danger, Hot summer
U-KISS- DoraDora, Stop Girl
EXO-History, Two Moons
CNBLUE- Love girl, I'm a loner
Infinite- The chaser
Miss A- Breathe, Bad girl good girl
Girl's Day- Oh! my god, Twinkle Twinkle.
You should also check out: SISTAR, Kara, BTOB, C-CLOWN, TVXQ, B.A.P., Block B, FTisland, 4minute, AfterSchool, Orange Caramel, Apink, etc.
Well, I got kind of excited, I think this would be enough for now, but there are plenty of other amazing groups missing that you should definitely listen to.
Hope I helped :3
