FP+ Spaceship Earth if you have to pick one. It's hot out there, and I also find the line area kind of chaotic since it's so near the entrance of the park. Easy for little ones to get distracted, wander off, WANT to wander off, start pitching fits, etc. Crush next, because IIRC, there's a limit to how many people can fit in that room. Then Nemo, I think.