Oh my list is long :^/ Here are a few though:
I truly can't stand Hwang Jung Eum, I just can't relate to all that excitability.
I dislike Kim Ha Neul, she always felt bland, uncreative and somehow conservative to me.
Of course I don't like Jin Se Yeon...
Very unpopular announcement ahead: Yoo In Na. She's too "cutesy' for me, even in her meaner roles. I know this is a weird thing to say, and also highly unfair because one shouldn't judge a person's looks too harshly, but I always felt like there wasn't anything definite or strong or edgy or intense or just captivating in her face... It's just... soft and... blah.
And I'm no Lee Seung Ki fan!