Anakin’s fall to the darkside was terrible. The whole notion that he was tricked into believing that the Jedi were attempting a coup etc. Yuck, yuck, yuck.
How would you have handled Anakin’s fall to the dark side instead? What would you have done instead of having him believe the Jedi were evil?
I’m not sure to be honest, but give me a decade or so (the time between ROTJ and 1994 when Lucas started writing the PT) and I could come up with something that was at least OK.
Obi-wan failed to give Anakin proper instruction - as he told Luke. But we never see that in the PT. Obi-wan always tries to make Anakin a proper Jedi. Anakin is just shown to be an arrogant prick, and borderline mentally ill.
Here is an idea - the PT starts in the Clone Wars with the Republic losing and the Jedi order decimated and desperate for more Knights. Anakin is not suitable morally, but Obi-wan is convinced it is worth the risk due to his great skill in the force and as a warrior in general. He is convinced that he can reform his ethics, but fails to do so.