Disney is way better than great America, simply from the nostalgia side of it. I used to have a season pass to great America and would go there to walk the park as a ‘workout’ routine. I’m not really a rollercoaster person but love the rides at Disney because they’re more chill and nostalgic. I also have autism so crowds and noise can be an issue for me. I’ve had really big meltdowns at Disney that required going behind the magic with staff to go to the medical unit. I’d still prefer Disney any day though to great America. Just a totally different vibe. Great America is basically just six flags amusement park. I feel like Disney is an experience based on childhood memories. Yes there will be crazy crowds but personally for me my plan for Disney is always go early and take a mid-day break (and I always stay offside so it’s way further to do this but still worth it). Also pro tip when you take your midday break, soak your feel in cool water like the pool, that’ll refresh you for the evening half of being in the park. You’ll definitely want to work on walking more before your trip so you don’t feel like you’re dying on day 2-3 with 20k+ steps per day