Depends on your child specifically, of course, but my ds10 has mild asperger's and we don't rent a car and stay at POP century a lot. Now that he's used to that resort, he honestly doesn't especially like staying anywhere else - it's his 'routine'. So be careful if you spend the money on the deluxe - cuz you might not ever (easily) be able to switch it up. That's how it is with my boy at least. Once he is used to something, that's what he expects and wants.
We use WDW buses...he is used to waiting in lines for them - usually counts the number of people and guesses and times how long the wait is (kinda has a thing for numbers). For the park lines - we arrive early and use FP's a lot - so we don't usually wait for longer than 20 minutes or so for rides. If you are going at a busier time or think he'll have difficulty with even shorter lines - bring a handheld electronic. I know for my boy at least...We could wait in line for an hour and as long as he has his dad's smartphone to play his games on (or usually just watching Mario Kart videos on
youtube). You could consider this if it would work for your child.