Honestly, I would pick SeaWorld. Aquatica seemed to me like they could have put more work into it when I went there. It was even sort of tacky. SeaWorld definitely had a more relaxed atmosphere and had more appealing things to do. Also, in SeaWorld you can buy passes to get to the front of ride lines, whereas in Aquatica you cannot. If you're looking for ways to stay cool, don't count SeaWorld out! The stingray petting area and the ride Journey to Atlantis are some suggestions for staying cool.