There are so many different types of rates. Entertainment, AP, Supersaver, AAA/CAA. I have a AP but should I be booking with that or is it better to wait for another type of rate?
It depends on when you're going and for how long. I usually book with the AAA discount first because that's usually the best discount when booking several months in advance. The AAA rate is comparable to the Supersaver rate of 4 nights, which is the typical number of nights we use. If you're staying longer than 4 nights, the Supersaver should be better.
The AP rate is the wild card of the bunch. Several months prior, the AAA rate beats it. However, Universal will release quarterly AP rates that are typically better than AAA rates.
As Damo mentioned, call the hotel and have them compare the rates that you qualify for.
After booking, keep checking for reduced rates, because should a rate drop, Universal will change your rate to the new lower rate if you request it.