Neither. The least expensive option is a four-day base plus a one day separate water park ticket. However, if the four parks is going to include hopping, then it is less expensive to add WPF&M.
If you go to the locked sticky Everything About WDW Tickets in this Forum, especially Post #18-A, you can get a lot more information. An easy way to get to the sticky is by clicking on the link in my signature. The ticket sticky is your friend!