Either one will be nice for your family.
BB has a longer family raft ride which can be accessed by a ski lift ride. These two rides were very much enjoyed by our children when they were small...and still are enjoyed by us all now that our youngest are almost seventeen.
TL has a salt water pool in which one swims with the sharks. You are given snorkle, mask and vest to float/paddle across the top of the pool viewing the fish (and sharks!) below.
Both parks have a children's play area that has smaller slides etc. for children...not too babyish for lots of kids...there is a height restriction, but I think most six year olds are under the limit.
TL is at the far east end of the Disney complex (near DTD) and BB is more on the western end, on the way to AK.