We love the water parks, and go there often.
I think everything GADisneyDad14 said above is spot on. I completely agree that it's truly 50/50 as to which one I'd pick. They're both fantastic. For thrill seekers, I think I might...just might...go with TL. Mainly because of it's wave pool. You have to see it. The waves are incredibly big, and amazingly fun. It's a zero entry pool of course, so young kids can go in and just go up their ankles and be fine. But for teens, they'll love to go into deeper water and catch a big wave. TL also has Crush N Gusher, which is kinda/sorta a roller coaster water slide, because it has jets of water that push you, even up small hills. But both have large slides, small slides, family tube rides, and lazy rivers. I love BB just as much as TL.
Both have plenty of shaded chairs available, so no worries there. You'll find a great spot to sit.
No, nothing costs extra as far as the rides go. They have gifts and food, but the attractions are included in the price. There is nothing like swimming with the sharks at either park. TL used to have the shark reef, but it is now gone.
Lines go up quickly and then drop quickly. The parks usually open at 10am (not always, so be sure to check schedules). No need to "rope drop" and show up 45 minutes early. Literally being in the park at 9:55am is more than enough time. Drop your stuff (or put it in a locker) and head for the big attractions. For the first hour you are there, the only limit to riding them is how fast you can get back up the stairs. There are stairs...lots of stairs. BB has a ski lift style chair lift, but I recommend avoiding it if you're in a hurry. It's slow and stops very often due to guests. Then from about 11am to 4pm it will be crowded. Long lines for the big ticket slides. That's when you do the lazy river, wave pool, smaller slides, etc... From 5pm or so until closing, the lines will drop very quickly. Also, if an early day t-storm comes through, it's also a good time to go, as it chases people out.
Also, they are currently testing a FP+ style system at BB if you go there. It's not done on
MDE. They have tables set up at a few rides. You go there and tell them how many FP+ you need. They give you a wrist band with a bar code and a return time on it. It's a 30 minute window. You return during that time and get to go to the head of the line. They were testing it on 3 rides....DDD, Teamboat Springs (the family tube ride) and Summit Plummet (the big drop slide). Frankly, it's only of value at Summit Plummet. Teamboat doesn't usually get a long line, and DDD the FP+ only brings you to the front of the line to get a tube, you still have to wait to ride...so it helped, but was still a 30 minute wait...better off doing that ride in the first hour of the day or last hour.
You won't regret either one, they're awesome!!!