We love the water parks and have been to both dozens of times each. In our opinion, neither is a full day park so you'll have all the time in the world to hit the thrill rides in each of them. Frankly, they both have good (but not super extreme) thrill slides/rides.
As for big drop slides, they both have them but I think Summit Plummet at BB is better than Humunga Kowabunga at TL. Humunga isn't quite as steep of a drop as Summit. You really get some good speed built up on Summit. There's a digital speedometer at the bottom so people watching can see how fast the rider is going (if it's accurate). I think it's something around 40mph. On the other hand, Summit is only one slide, so once the line builds, it moves slow. Humunga has 3 slides side by side by side, so it has greater capacity.
BB has a second big drop slide, right next to Summit, called Slush Gusher. It's a 3 hump drop. Starts with a drop, levels out a bit, drops again and repeats. On the last drop you actually will catch a little air as your body comes off the slide a bit. I'd bet you're no more than 1" off the slide, but it feels like you're 3' off. It's scary the first time you do it.
TL has Crush Gusher, which BB doesn't have anything equivalent. It's a tube ride that's sorta, kinda roller coaster-ish. It doesn't just go downhill with the force of gravity and flowing water. It has jets along the path that push you up small inclines. It's really fun.
BB has Downhill Double Dipper (aka DDD). It's a side by side tube race. Not super extreme, but fairly quick and a lot of fun.
TL by far has the better wave pool if you're looking for extreme. The waves are HUGE and if you're a good swimmer it's a blast to play in. I love it and can spend hours in it. BBB wave pool is small constant waves. It's still fun, but not extreme, and frankly makes me sea sick after a while if I'm in an inner tube.
BB has an 8 wide mat slide race. Not really super fast, but fun.
They both have good individual tube, mat or body slides.
They both have good family tube rides. Neither is extreme, but if I had to pick the more "thrilling" one it would be Teamboat Springs at BB. Your raft slides a bit higher up the sides, it's fun.