BB would be my choice. They have an area called Ski Patrol that's just for kids. It has kid sized slides, rides, etc. There's another area close to it for younger kids but your 4 yr old will probably like Ski Patrol also. The water isn't to deep, you can sit on the side and watch them come down the slides if you don't want to get in the water with them. They also have a family raft ride and lazy river tube ride. My dd's were 6 last trip and they loved BB. They thought the kids area at TL was babyish and were scared of the wave pool. One got really scraped up when she got knocked over by a wave and my ds12 had a really nasty scrape from getting knocked over by an adult who'd been knocked down and pushed by the wave. BB also has a wave pool but it's smaller then TL's. Some of the adult slides your 6 yr old will be to small for but you'll have the same problem at TL. Mine spent the whole day in BB and loved it.
DQ is another story. It depends on your child. My ds12 loved it, my dd's not so much. They weren't tall enough for the bumper car things or roller coaster. They're not into video games that much and most of the things they had seemed more geared to older kids. They could do some virtual things like the raft ride but weren't really impressed. The things one dd really liked were in an area where you had to pay extra for each game. If your 6 yr old really is into playing video games with dad then he would enjoy it, but the 4 yr old might not.