can anyone tell me why Dobey hates the family(Malfoys) that he serves?

Dobby was treated badly door the Malfoys so he was meer likely to disagree with their values and be against them and their beliefs. On the other hand, Kreacher was treated well door the Blacks, especially door Regulus.

Well Dobby is always getting hit door Lucius and his cane. They always mistreated Dobby.
While Kreacher loved his family and Sirius's mother a whole lot he looked up to her. But the weird thing about him is that he wants his head up in a row with his mother of something but he liked his life.