Your question about Steinbeck's Of Mice and Men is very much an opinion question. I'll tell you my answer and give you some reasons for my opinion, but you really have to answer the question for yourself.
I feel sympathy for both. Curley's wife is ignorant and uneducated and she uses what she's got. She is also a misfit in the novel. She is isolated and mistreated, and is a woman in a man's world. What options does she have? And, of course, she's killed.
Lennie doesn't mean to kill her, of course, and you can't help but feel sympathy for him. Like Curley's wife says, all he talks about is rabbits. That's pretty much all he thinks about, unless he thinks about something else that he can pet--like mice or puppies of Curley's wife's hair. Society in the novel has no real place for him. He tries not to talk to Curley's wife, but of course she won't let him get out of it. She doesn't understand the danger.