We've done each one dozens of times, in fact we're doing a trip next summer and going to only the waterparks. Reality is that they're about 50/50, they're both fantastic. They both have great slides. Each one has unique "big" slides. The biggest difference is in the wave pool. The BB wave pool has small and continuous waves. It's like bobbing out on a choppy ocean. I enjoy it, but it does make me a bit seasick after 20-30 minutes. The TL wave pool has huge, gigantic waves that come once every two minutes or so. If you're going to go into the deep end of that pool, you need to be a strong swimmer...though the same is true at BB. Both are zero entry pools, so if your child isn't a strong swimmer, keep them in the more shallow end. Some people will say the TL wave pool is more dangerous, but I would completely disagree with that.
Both parks have really fun lazy rivers and smaller slides.
If you like the TL theme better, then go there. You'll love it. Hit the big slides first. Park usually opens at 10am. Get there at 9:55am, that's more than enough time ahead. Rope drop crowd is very small. The slides you'd want to do first are Humunga Kowabunga, Miss Adventure and Crush n Gusher. From there, do the smaller stuff, the wave pool and lazy river.
