My family liked both of them, for different reasons of course. It's really hard to decide. Neither of them were very busy when we went in April. We did both parks in one day, spent a few hours at each.
I really liked BB just for the setting, plus they have some real fun slides. BB has the best kids area of the parks, my girls, 6 and 7 at the time really liked the zip line.
Then we went to TL and couldn't get them out of the wave pool, along with myself and my wife....that thing is an absolute blast. I think the snorkeling pool at TL is a joke, especially after you just went to Discovery Cove.
It's a tough choice, try em both...but if I had to suggest, most suitable for kids would be BB.