Park Shin Hye
Lee jong suk
Kim So Hyun
Jang Hyuk
Yoon Sang Hyun
Joo Sang Wook
Lee Byung Hun
Ji Jin Hee
Jung Woo Sung
Choi Jin Hyuk

Oh god why do I love these old men?!

For actress... Kinda difficult but I choose
Moon Chae Won and Lee Min Jung.
I adore Park Hae Jin! But Lee Sang Yoon is also at the top of my list.
Ji Chang Wook
Lee Je Hoon
Lee Jong Suk
Jung Woo Sung
Kim Rae Won
Gong Yoo
Yoo Ah In
Park Hae Jin
So Ji Sub
Jung Kyung Ho 
Lee Jin Wook- smoking hot!!

Etc... There's just too many I like 


Actresses

Park Shin Hye
Ha Ji Won
Choi Ji Woo
Lee Jong Suk
Park Bo Gum
Ji Chang Wook


Kim So Hyun 
Park Shin Hye
Park Bo Young
Lee minho
Ji sung
Joowon
moon chae won

In no specific order, judged for their works, independent of scandals: 

Seasoned guys:
  • So Ji Sub
  • Hyun Bin
  • Song Seung Huen
  • Jang Hyuk
  • Ji Sung
  • Nam Gung Min (only in Romance or Drama, not in Comedies)
  • Jo In Sung
  • Song Joong Ki
  • Lee Min Ho
  • Gong Yoo
  • Ji Chang Wook
  • Park Yoo Chun 

Younger guys:
  • Park Hyung Shik
  • Kim Myung-soo (aka "L")
  • Yook Sung Jae
  • Seo Kang Joon
  • Yoo Seung Ho
  • Jung Jinyoung

Non-Korean: 
  • Sakurada Dori (Japanese)
  • Yamazaki Kento (Japanese)
  • Roy Chiu (Tawainese)
1.Yeon Woo Jin

Hyun Bin
Seo Kang Joon
Lee Dong Wook
Lee Kyu Han
Jung Kyung Ho
Choi Tae Joon
Yeo Jin Goo
Kim Soo Hyun 
Lee Jong Suk
Gong Yoo
Yoo Ah In
Seo In Guk
Song Joong Ki 
Park Bo Gum

... I'm trying to keep this list to a minimum, I really am
Song Joong ki, Park Jae Jin, Lee Dong Wook, Seo In Guk, Lee Jong Suk. 
Ji Chang Wook
Seo In Guk
Lee Joon Gi
Kang Ha Neul
I don't know why but Im inlove with Lee Dong Wook
Ji Sung : what an amazing actor. I like his acting in "Secret" & "Kill me Heal me"
Gong Yoo : his face has all emotions & he can act some charactor in a moment ..
Ji Jin Hee : best for "emperor charactors" like in Dong Yi ..
Song Seung Heon : I like he in "Saimdang" , wonderful ~