I did Universal and thought it was ok. I have still not done Knotts. If you are looking for a good Haunted Experience but not nessecarily the rides I heard that Queen Mary had the best mazes and for a good price. I think we are going to do that this year instead of the Amusement Parks because we heard so many great things.
Otherwise I liked Magic Mountain not for the best mazes (they were all only ok) but getting to ride the rides with changes and no lines was great! But I haven't done this in about 5+ years so it might have changed alot.