I would also say BB. BB has two kids areas, Tikes Peak was perfect for my 2yo, and Ski Patrol Training Camp was great for my 8yo (although she still liked a lot of the grown-up slides, too).
At TL, there is just one kids area, Ketchakiddie Creek. The slides were too small to be any fun for my 8yo, but since there's no "tweener" area, there were still a lot of older kids running around there. The older kids liked the sprayer things, but there was too much water in the face for many of the little ones. My 2yo was comparatively so much more relaxed and had so much more fun at Tikes Peak, where it was only little kids.
As stm said, the family raft ride at BB just blows the TL one out of the water! (pun intended

) Lazy river is the same at both. My kids liked the wave pool at BB better, too. The one at TL has one gigantic wave that comes along every 15 minutes or so. It terrified my 2yo. My 8yo loved it, but would get bored waiting for the next wave. The one at BB has smaller, continuous waves, so while not as exciting as TL's waves, at least you didn't have to wait around for the next one.
Both parks were a lot of fun, though. You really can't go wrong, and TL has Crush 'n' Gusher, the "roller coaster" slide, which was really fun and different.