Blizzard Beach! I personally like Typhoon Lagoon better because I feel Blizzard Beach has too much of the park dedicated to mid teens and younger, but that probably makes it the best for your situation. It has the Ski Patrol Training Camp for big kids and pre-teens and a huge splash area for 48 inches and under.
But why not both? If you go with the water parks and more option add on to a regular ticket you get as many entries to the water parks/golf course as you do park tickets. So like 5 day 1 a day park ticket = 5 park days + 5 Water park and more options. The water park are single use and can be used in the same day without interfering with the core four park tickets