Splash has the best story but Dudly Do Right and Journey into Atlantis have the best drops and coaster elements.
For the record, I do not consider rides like It's a Small World and Pirates of the Caribbean water rides because you don't actually get wet on them (okay, you can get misted on Pirates, but nobody rides it to get wet). Instead, these are dark rides that just happen to use a flume system as a method of conveyance.
People ride roller coasters for the motion sensation - you don't see riders popping motion sickness pills before they ride - they know what they are getting on.
There is nothing I like better than being on a Popeye raft with a family who are in ponchos and get off just as wet as those of us without. Even with a poncho, it is a luckY rider who gets away without a good drenching.
Solution - take a change of clothes in the locker and just ride the water rides just before lunch or at the end of the day.