Typhoon Lagoon is the better park. The ambience is far superior. The wave pool is great (but crowded). The slides are about as good. The snorkeling is fun, but a little cold.
I would agree that the big slides at BB are faster and better, but not enough difference to make up for the superior landscaping at TL. My kids, who love Summit Plummet at BB, still agree that TL is better.