Both are tremendous, however, the technical aspect of American Adventure is so much more advanced that it is hardly comparable. If you were to see the configuration under the stage of the scenes and how they must move into place at the right moment, it would completely blow ones mind. CoP was a major technological marvel in 1964 when it first appeared at the NY worlds fair. For it's time, it was magical. It's one of the reasons why it must stay. It is the mother of all we see now. It is still a marvel, even today. When was the last time you experienced sitting in an auditorium and having it move you to the next scene? It's still great, but, American Adventures is nothing else if it isn't an engineering miracle.
That may be just me though, because ever since I first stepped foot on WDW property over half that "magic" that I got out of it was not the show, but, how they made it work technically. I would think that for those that cannot change a spark plug in their car, it would also be an incredible thing to imagine and incorporate in that experience.