Well, I haven't been to either, yet...
But, my very strong inclination would be to pack your beach towel(s)!
It seems that very seldom are the ones provided adequate.
Also, if you pack your own brightly colored towels, you are visually staking out your claim amidst the see of provided towels
Does Aquatica have towels available?
Or, are you planning on buying them there?
I read all the reviews after Aquatica opened, and they are very miixed.. a lot of disappointment that it does not live up to the hype, (except the fast moving not-so-lazy river!) and is overpriced.. fees for everything.. etc... I checked out the photos posted on Tripadvisor, and decided that Aquatica might not be the top of my list.
I hope you get some more input on your questions!
We will be traveling this Spring.