I've always thought the problem with the Prequels wasn't that they were worse, it's that movies got better. Sure, the Originals are still still fun and even have their moments of good one-liners, but for the most part not having grown up with them I was never terribly by the writing of the series.
But they absolutely needed to be there, when they came out.
I have no doubt in my mind that Star Wars pretty much saved the film genre I love by being both different and in a lot of ways better then most of the other things that were out then. But the key word there is then. As films coninued on the revolution Star Wars helped to create the series itself never learned to change with the times. The Prequels weren't too different from the Originals, they were too much like them.
And when you strip out all the historical relevency all we're left with is an enjoyable set of movies about wiz-bang-shooty-fun set in a fantasic universe, nothing more, nothing less. And if that's all I'm there for, I'd rather watch the ones with the better effects and art style.
Episode IV is the best though, closely followed by III. You can't tell me the extermination of the jedi didn't give you chills.