At Universal Horror Nights, you get a high level of quality and detail in their mazes, and their scareactors are high energy and in your face.
Knotts could learn a few things from Universal or even Tampa's Howl o Scream Event.
Knott's has monsters who can create their character and has very creative scares in and outside of the mazes. The Hanging blows Bill and Ted's out of the water.
My vote is for Knott's.
I went to both, but it was at least 15 years ago. I enjoyed them, but they are one shot deals. Once you go, the thrill is gone. I like them both. Knott's had better atmosphere and mazes. Universal had better movie tie-ins and the tram ride was great. Knott's had Elvira at the time and she was a gem to see. Universal knows how to put on the show.
Overall, I recommended both, but Knott's has the edge.