We just did BB and TL last week with our dd4 and dd1. We thought we would prefer TL based on what others had said. However, Ketchakiddie Creek at TL was a longer hike from the entrance and a longer trek to food and bathrooms. Also, the wave pool at TL was a bit too intense (even way over in the overflow "coves") for my little ones. My DD4 did like the tube ride, but the slides were really, really slow. The CM said they only wax them once every other month. My DD1 was actually a little bored because the water level was pretty low in most of the fountains and it was more like sitting in puddles (clean puddles).
BB offered more in Tike's Peak for our dd4 and dd1. DD4 liked the faster slides (and there were more of them) that were still age appropriate for her age and limited swimming ability. There was a tube ride and some regular water slides. There was also a set for younger children (probably about 2 year olds) that were padded and very short. My DD1 liked these a lot with my husband at the top and me at the bottom. Finally, what I really liked was that there were three slides that were large enough that parents could actually go down them with their children. They weren't very long and the landing area was very shallow. However, this was a lot of fun because I could take dd1 down on my lap and "race" my daughter in a setting that was safe and developmentally appropriate for her.
Tike's Peak at BB was a lot closer to the entrance and food and they had a shallow swimming area that was a bit deeper than TL. My dd1 liked this better because she could sit in the water and splash (it was no deeper than bath water would be). I liked it because the pool was cushioned in this area which was much easier on my knees when I knelt in the pools with her than the cement areas.
We liked them both, but I would go with BB if you had to limit yourself to one.