I seem to be in the minority round here, but I actualy quite like Wet 'n Wild, and if given the option to go to only one water park, Id probably chose that. Why ?, Well I think its a combination of the quantity of rides, and rides that I think are better, and also the relative lack of queues (unless we've just been lucky every time we've been there).
Im not saying I don't like TL and BB, they are both great places in their own right, and they are well themed, which is something Wet 'n Wild clearly lacks......but im there to have some fun, and the decor/theme is of secondary importance to me.