Considering the fact I have been to both parks, I would say that by a landslide that Universal Studios would be the top pick for preteens and teens hands down because it is action oriented.
There is so much to enjoy at Universal such as Kongfrontation, Earthquake, Jaws, Back to the Future, and Twister among others.
I think they will definitely love it as well as find it very exciting; remembering their visit from years to come.