This is why Bush is fundamentally a terrible candidate, regardless of his political skills.
His brother's term was a disaster and almost universally seen negatively.
Bill Clinton's term was successful and generally seen positively.
A Bush vs. Clinton race demands, not just invites, that comparison. Maybe it isn't fatal, but I don't see how he survives that. And, if you're the moderate candidate and you don't have a strong electability argument, you're cooked.
Bush's approval ratings have been steadily improving since leaving office. It sounds to me like you are stuck in 2008... He is not the universally hated man he once was. I would provide a link to back up my assertions but I guess I need more posts for that so just google it for proof.
With ISIS and everything going on Bush's favorability will only improve as his actions in the middle east will appear more and more justified. Of course you and I know this is bullsh**t but the public is not you nor I.
Every president's approval shoots up when they leave politics.