Definitely AP offers the best discounts on the room, sometimes as much as 50% off rack rates. This is followed by the Fl. resident discount, which is usually almost as much as the AP discount and sometimes the same as.
AAA is a small discount in comparison, like 10 or 15% off rack rates, but better than nothing!
The best discounts can be found when the resorts are in their "value season" and the AP or Fl res. rates are in effect. The discounts are not guaranteed and they only have a certain percentage of rooms set aside for the use of AP or Fl Res. rate discounts, so often the basic standard rooms (cheapest) go first. Once a discount is announced, you should make your reservation as soon afterwards as possible to give yourself the best chance at the room category and resort you want.
Also, they may not be offering the AP discount or the Fl res. rate discount during the time you want to go.