My family loves water parks and we make it a point to go every time we are in WDW. It's a nice, relaxing place to take a break from the heat and crowds in the parks.
Whether BB or TL is better is an entirely subjective thing. Personally, I love TL and don't have any desire to go back to BB. I think it's the atmosphere I don't like. I have fair skin and burn really easily, if I don't have a base tan going and I found that BB offers very, very little shade. It's a ski resort theme which may appeal to those who have never been, or haven't often been, to a ski resort. We have ski resorts locally and go often so the theme really doesn't appeal to me. Plus, they have all these concrete "snow banks" that are painted white which means the sun just bounces off them. The steps to the attractions are just metal staircases and there is no sand anywhere and very little foliage.
TL has sand all over the place and lush, tropical foliage that offer tons of shade all over the place giving shade which I appreciate and the ques have all kinds of fun water spouts and fun themed displays to look at. It's just all around a better experience in my opinion.