Okay, well it all depends on what you want and what you are after.
Wet 'n' Wild
It's closest to you if you're on I-Drive. It is quite dated these days. There's too much concrete for my liking - when the sun gets hot, so does the concrete
Aquatic
Haven't actually been there, but did look at a lot of the promo pictures/videos when it first launched. Again, it's a bit like WnW, although has a bit more theming. From reports though, there is very little shade, which is something you really need at a water park. The other thing is they have the "really cool slide" where it takes up under the water pass the dolphins ( i think) and other creatures, however, you are going so fast that you don't really see it anyway, or so other have said.
Blizzard Beach
It's great for those who want to really let loose on the slides; it's more adventurous than TL, what with Slush Gusher and Summit Plummit. The rides are that little more hardcord, and therefore it's usual guests are teens and adults, although there is still plenty for the rest of the family. There are plenty of sun loungers, shade and while the paths are concrete, they do have sprinklers that keep them wet and a bit cooler!
Typhoon Lagoon
It's our preferred choice. The rides are a little bit gentler, although there are still a few hair-raisers/bum burners (our nickname for Crush n Gusher). There is plenty of sun loungers here too, shade and wet pathways. The wave pool is the best, and as random as it sounds, is normally where we spend most of our time. My mum and sister are not keen water slide people - it's only me that's ever done Der Stuka. So it's good for all of us there.
Adventure Island
Somewhere I've always wanted to try, but since it's out in Tampa (opposite Busch Gardens) it's difficult to get to without transport. However, I assume that it will be like WnW and Aquatica, in that it will be quite concrete like. It is also more geared towards water slide enthusiasts.