I would say it depends on the ages of your kids and how confident they are with the water and rides. My nephew was 5 and not tall enough for all of the rides at Aquaventure. Wild Wadi and Yas have more 'white knuckle' rides suitable for older, confident swimming kids. Aquaventure is more suited to younger children as my niece (8) and nephew (5) enjoyed the kids area and the lazy river bit the most. HTH
http://www.aquaventurebirthday.com/?CID=em_Birthdaycampaign_atp_07042015&utm_source=email&utm_medium=crm
Thats the link to register your kids birthday and for the free pass...
I also agree aquaventure all the way! Have FUN