I only have Yang Zi on weibo. 

1. Demo 

2. DT

3. Grunt 

1. Demo. The precious cinnamon roll. Want to hug him all day.

2. One. He's really cute too and even though we don't see much of him, I really liked him.

3. Grunt. He's 33 but wow he looks younger than Li Xian lmao

1. Gun

2. Grunt

3. One

4. 小米

5. 97

6. Demo

7. DT (sryyyy...)

My favorite are 97 and Little Demo >_< I really enjoyed the scenes where k&k boys tease HSY (≧▽≦)

#1 is Gun 

#2 is DT

#3 is ALL THE 4 MEMBERS OF K&K (97, Grunt, Demo, One)

#4 is Little Mi

#5 is Ou Qiang / All 

97 or Grunt! Honestly 97 is like a sunny boy next door whereas Grunt seems like someone I can relate to!!! 

From the drama itself I actually really loved Xiao Mi. If I were to put my favorite characters it would be:

1) Mi Shao Fei

2) Sun Ya Ya

3) Grunt

4) Ai Qing

5) 97

6) Demo

Of course I also really liked the other characters but these characters really stood out to me.