To start with her personality and charisma just grates on me. I don't feel like she would make a good figurehead for the nation. One of the few things I do still like about Obama is that he's good at his speeches and can pull off being a relatable figure.
Clinton is nothing but dislikable to me and her time as Secretary of State hasn't given me much hope that she would be a good diplomat either.
Her positions are almost entirely determined by the voter climate at the time. It's hard to tell what exactly she is or isn't for because her "opinions" at the time are either a complete non-answer or whatever she feels that people want to hear. I hated her answers during the last debate and thought she completely failed at the benghazi hearing. (Yeah, it was intended as a political hit, and she treated it like one, and I guess that's fair, but that means that nothing really got settled by it.) Granted, I didn't watch all 11 hours, but the clips that keep getting passed around by both sides of the media are really really distasteful. And it's painful to see the left hold it up as proof of her character and the right hold it up as proof of her guilt of something.
Then there's the whole Clinton/Bush Dynasty that's been controlling the country for a large chunk of the last 30 years. I don't want to see that continue, even if that's a little personal and not really based in logic. For the same reason I really don't want to see Jeb Bush in office either.
She's a career politican and it shows, and I don't like that. If Sanders doesn't make it past her I'll have to seriously consider voting third party or Republican because I don't think I can vote for her.
But yes, as RedKing says, I'd rather marry a republican than Clinton, but I'd also vote for a republican than clinton... if the republican weren't too crazy...