If you just don't like something, 좋아하지 않다 may be a better choice, although 싫다 can be used too.
For 싫다, the voice tone and adverbs can vary the strength widely, but it's always stronger than 좋아하지 않다.
e.g.
- 저는 고양이를 (별로) 좋아하지 않아요 = I don't (particularly) like cats.
- 저는 공양이를 싫어해요 / 저는 고양이가 싫어요 = I dislike cats. (it sounds like a relatively mild dislike).