Jun Ji Hyun my forever fave
Park Shin Hye
Kim Go Eun
Jang Na Ra 
Jeon ji hyun and Moon Chae Won
Lim Su Jung is the best shes back in chicago typewriter
she's still pretty and baby face although shes 37
Kim So Hyun & Song Hye Kyo
Gong Hyojin and Song Hyekyo!
Kim Ji Won, Lee Da Hae, IU, Kim So Hyun, Park Bo Young
Kim Go Eun
Park Bo Young
Song Ji Hyo
Gong Hyo Jin

Seo Hyun-jin

Jang Na-ra

Gong Hyo jin

My top 6 korean actresses: 

Kim Go Eun
Han Hyo Joo
Moon Chae Won

Bae Suzy
Jung Da Bin
Jung So Min

One more: Kang Ji Young , she is korean, but acts in many jdramas and can speek in japanese very good. :)

Shin Se Kyung

Hyeri

Jung So min

Han So Hee recently joined Moon Chae Won on the top of my favourite actresses list. Otherwise, Kim So Hyun, Kim Yoo Jun and Lee Bo Young.

Lee Ji Eun (IU), Seo Yea Ji, and Park Min Young