We visited by TL and BB this summer with my sons, 12 and 9. They are strong swimmers and like "thrill rides". They enjoyed both water parks, but I think BB was their favorite, since the rides were more of a challenge. Although the older one was afraid of the shark tank at TL (he went on the biggest of rides, but doesn't like to swim with fish around him - we coaxed him in, but he didn't enjoy it) and the little one never figured out how to use the snorkel, but enjoyed the shark tank at least three times. I thought the shark tank was one of the best parts.
I personally enjoyed both TL and BB, and would go back to either one. Since we didn't have anyone in the little kids area, I'm not sure which is better for that age group.