He already watched Hana Kimi, My Gf is a Gumiho and Gu Family Book and loved these.
Which of the following dramas do you think should he watch next?
Iljimae
Youre Beautiful
King2Hearts
Rooftop Prince
I think that he should watch Iljimae, King2Hearts or Rooftop Prince (I like King2Hearts and Iljimae better than Rooftop Prince though). I don't know your brother's taste in dramas, but You're Beautiful is more from a girls POV in my opinion.