Universal is terribly crowded especially Islands of Adventure. It seems "Islands" cannot handle the crowds and they do not have enough sit down experiences (shows, etc). I actually preferred Universal with Transformers, Terminator 2, Horror Make-up show, eating, Simpsons Ride (old Back to the Future), Shrek 4D, etc. Despicable Me is going to be a long wait not matter what as it is a low capacity ride,

I personally have a Disney annual pass, but not this year. I am skipping Xmas this year (as a teacher, I am off the evening of the 23rd which is too close to the holiday to get out of town). I will miss it. Maybe next year.
Disney is really crowded at Xmas, but there is enough to do that has little wait such as movies and shows that can easily break up the longer lines. Use your fast-passes also. It is more manageable than Islands.

Hotels around Xmas are expensive at Disney. The cheap hotel was $1300 for 7 nights. I opened up two credit cards to help pay for it Disney Chase (which was $151 credit off of $500, it saw $200 but it is really $151 after paying $49 for the card for a yer) and AMEX ($150-250 off a $1200 purchase or something).