I wouldn't say that Bush "irritates" me. His policies have been absolutely atrocious, and the war he pushed for claimed the life of a friend of mine... I'd say he pisses me off much more than irritates me.
Hillary, on the other hand, irritates me. I agree with much of her policy, but then she goes and favors censorship in video games and nanny legislation banning their sale to minors. She also has a tendency to use ugly political tactics. That's irritating to me because she would be a great politician if she didn't seem so damn petty.
So I'd say Hillary was more irritating and Bush was more despicable. But I voted Bush anyway because I think that's more in line with what the OP intended with his poll.