iAn Islands day, with a mid-day stop at Mythos, cannot be beaten. The rest of the food is poor, but regardless.
Really just hope with the success of Nintendo both in theaters and in the park, they begin work on their initial plans for converting Lost Continent to Zelda, because it would give the park just another world-class land.
Island's main issue is it lacks much depth beyond rides, especially with its two theaters sitting empty. That said, its ride line-up is unbeaten anywhere, except maybe Disneyland park in Anaheim.
Animal Kingdom is easily the highest-quality theme park in Orlando, it just severely lacks in quantity. Animal Kingdom could stand to double its ride count. Its show, walk-through, exhibit, and atmospheric sense are undefeated. Legit all it needs is rides. You could add five rides before adding another land, which is what they should do and would be far more economical.
To me, Magic Kingdom just falls so severely short of what it should be, given the crowds. It also lacks a headliner, which all other three WDW parks have, so really falls short.
Epcot earns massive points from me for both having great depth, and now with Guardians, a headlining attraction. Epcot is truly something unique at WDW. If it wasn't for Epcot (and Animal Kingdom) there would legitimately be zero reason to visit WDW over Disneyland. Both parks are very special and unique and provide something the others just don't.
Hollywood Studios just lacks across the board, atmosphere, ride count, shows, all of it. It only excels in ride quality, but Islands has both quality and quantity, in addition to its awesome atmosphere.