I agree to a great extent with the original poster, and I personally prefer the prequels (yes, despite Jar-Jar and the rest, but to be honest, ROTJ had Ewoks...) due to its much deeper story and highly Machiavellian political plotting (see it as a light-version of a political thriller, a very light one occasionally...). Especially anyone who has studied political history on university level or above should really appreciate the underlying plot of the PT.
Still, I hold the OT in very high regard, and consider these also some of my favourite movies.
Both trilogies are really good, and in one way, I would compare the OT to a T-Model Ford and the PT to a Ford Mustang (first generation). In one way, the Mustang is far better than the T-Model, especially when it comes to pure technology, which makes sense after a few decades of continuous development and research. However, the Mustang would never be able to match the impact of the T-Model when it was launched; suddenly the average American could afford a car, and the idea of the assembly line revolutionised our modern society. In many ways, it was the first modern car. The Mustang was just another one; it may have been a good one, but it was not unique, nor did it revolutionise the 60s.
My point: decades of development (and a significant increase of budget for the movies) make a direct comparison between the OT and the PT rather unfair, but while the PT did not really alter our way to look at sci-fi movies, nor computer animation, etc., the OT really did change entirely our conception of sci-fi, of heroics and epic stories, of computer animation in movies, and it did perhaps even change the movie industry itself.
I would therefore say, depending on what you look at, depending on what you consider, the OT as well as the PT could be seen as the better.
Just my thoughts.