One of the biggest things that bugs me about the prequels, in retrospect, is that it's about the fall of the Republic at all. From watching the Original Trilogy, you get the impression that the Empire has been around for a very long time. Long enough that nobody living can remember a time before the Empire. Then, in the Prequels, it turns out that Luke Skywalker was born in the Republic. How crazy is that?
The way I would have done it: have Episode I be about introducing the Clone Wars, and via Anakin, introduce us to everything going on. Anakin should the everyman character who just like us knows nothing, so he has to be told, meaning the audience gets told and the exposition is not so much exposition. Have Episode I also be about the end of the Clone Wars, thanks to Anakin, Obi-Wan and whatever band of allies they may bring along with them. In Episode II and III, jump time ahead to give longevity between the time of the Clone Wars and the time of Episode IV. Anakin and Obi-Wan should be older men, who you can tell are close friends and have been on numerous adventures together since the last Episode, and have a brotherly relationship. This should be time spent explaining the increasing corruption of the Republic and the rise of insidious forces in them, and the Republic itself becoming bad because of it's corruption and infighting and chaos. I would have had Episode II be about the fall of the Republic and the rise of the Empire, Anakin's fall from grace assuming he is doing what is right and necessary to protect the ones he loves, and possibly Anakin becoming Vader (in non-cyborg form) or otherwise the right hand of the Emperor. In that form, of the right hand man of the Emperor, Anakin should not assume the Empire is evil or that he is evil: no villain believes themselves to be evil. The Empire at that time should not be apparent as totally wicked. It should be like Nazi Germany in the aftermath of the Weimer Republic: selling out from the belief of doing what was necessary, and trading freedom for security. No knowledge of the genocide and evil, though existing in the culture and accepting the culture that allows it to go on in reality. And Episode III would be some years past that, the increasing culmination of the authority of the Empire and increased malevolence of the Empire, Anakin growing more wicked with it, Anakin pushing away those who love him and whom he is trying to protect in the quest to protect them, and Anakin growing increasingly evil (in fact) by going along with what's happening, making excuses for it, and growing angry and bitter and cruel as everything goes to hell. I would also have Vader birth his children in this time (he should have them at middle age than just like 19 or whatever it was), knowing they're his, but assuming they've died for whatever reason; that could in fact be what pushes him even further into evil. That all culminates in Vader fighting his old master and comrade, with the hellish environment around him representative of his inner torment and evil and chaos, finally being defeated in battle, in a mirror of Obi-Wan's defeat in Episode IV, and being burned and maimed, becoming ugly on the outside as he is on the inside, being taken and turned into a cyborg by the Emperor, and his outside robotic form representative of his coldness and lack of humanity. And then set up in that Episode the rise of the Rebellion and the beginning of the Civil War. Fill in any blanks from there.
And again, I very much feel that George Lucas' rise and fall from grace and what he is and the way he has been in relation to himself and everything is, in meta form, a muuuch better prequel than what was made. Take George Lucas' life, replace the names with Star Wars characters, and shoot it and you have a much better prequel. Lucas went into Star Wars innocently enough, had married, and was planning all this great things. And the success of Star Wars led him to be beloved. But that took a toll on his marriage, making him more distant and too caught in his work, and his relationship crumbled, all the while with him assuming he was getting security for his family and that he'd settle down eventually. And those films too their toll on his health and his marriage. And that marriage ended, and George Lucas took an emotional hit for it. All the while being beloved. And then he comes back, and does what he thinks is right with the Special Editions and the prequels. And it upsets people with his behavior and attitude, but Lucas thinks he's doing right, and wags an accusing finger back at his critics, which further alienates the fan base, and he refuses to do so many things and sets his foot down in stubborness, further upsetting his fanbase. And he goes from this beloved figure we assume is perfect to something quite different. And Lucasfilm and the Star Wars franchise is representative of the Empire, being Lucas' devotion for all that security and success, which he gets too caught up in, thus obliterating what he wanted it for, and it becomes increasingly bureaucratic and cold. And it becomes about merchandising, and begins to lose it's soul in that.
Insert Boba Fett into that story, and you have a kickass Episode I-III. You could put down why the prequels weren't that great to the fact that Lucas emotionally would not go too close to that, or at least not in a fashion of maturity and well rounded perspective, and that's the kind of story the prequels always had to be.