Right, lots of reasons that have nothing to do with her being a woman.

"I just don't like her."
"I just don't trust her."
"I just can't relate to her."
"She just doesn't seem like a leader."
"She doesn't have the stamina."
"I can't stand the sound of her voice. She reminds me of my first wife."
"I can't stand the sound of her voice. She reminds me of my mother."
"I'm going to vote for Donald Trump because Hillary Clinton tells lies."
"I'm going to vote for Donald Trump because Hillary Clinton is corrupt."
"I'm going to vote for Donald Trump because Hillary Clinton is too old."
"I'm going to vote for Donald Trump because Hillary Clinton is fat."
"I'm going to vote for Donald Trump because Hillary Clinton has been on TV forever, time for something new."
"Ew! I can't vote for her. Her clothes are so frumpy!"
"Uh, something about her emails. I don't exactly know what."
"I'll never vote for her because she didn't leave Bill Clinton when he cheated." 

Nothing to do with her sex. Right.