The effects of the prequels are far better as well; as good a job as WETA did they don't hold a candle to ILM. Just look at the cave troll from Fellowship--god that was awful.
The prequels take a lot of shit because of the lack of "real" locations, but if you look at the quality of the work itself, there is nothing in LOTR that really tops its SW counterpart. Even the breakthrough work on Gollum is surpassed by the subtle and wholly "human" realization of Yoda (especially in ROTS, where he's heartbreaking). Also, while the Trench Run has the benefit of great writing and characterization, the Pod Race as a set piece alone is such a fantastic achievement of effects and editing that I feel it never gets enough credit.
Bottom line though, and this is the difference for me, I prefer Lucas's traditional, Ford & Kurosawa-inspired frame compositions to Jackson's ameteurish b-movie bag of tricks (the canted angles, "zombie-cam", overhead helicopter cam"). They are both storytellers of the highest order but I find SW functions better as capital-A art, an aspect that is rarely discussed when comparing the two.