Coming from parent of disabled adult ...
First check school districts that are tops for special education / services. That will likely also be some of the better districts overall. Orange County (Orlando) is among the higher rated, and then the others are 2+ hours away from Disney.
We have home in St. Johns County and I believe they are rated #1 for services. We are past school age but I know there are also adult programs that your adult may be interested in. We did take him to the surfing that happens once a month and what a great program. There are lots services in the area.
The other higher rated districts for services are in South Florida, both coasts. These areas might be more expensive and more impacted by weather. For my POV I would avoid those areas, staying central or more north.
Districts in Florida seem to vary greatly so it is important you narrow to the right district AND I would look at the individual schools and find the area in the county that you think is best. Example Orange County, has great reviews in some areas, not as much in other areas ~ but housing costs will reflect that as well. St. Johns County has several new schools in areas that are full of new housing, shopping, parks etc.
I believe that where the better school districts for special needs are .... you will find more of the adult services, public and private ... as folks transition out.
But be sure you look at housing costs, insurance costs and real estate cost if buying, and know cost of living in not low as it was in the past. Good luck!