I know 3 dogs where the families purposely cross-bred a Border Collie and a Black Lab (3 litters w/ 1 male lab 2 different female border collies)
Not only are these dogs some of the easiest to train, but they are absolutely the smartest dogs I've ever seen and the best behaved, even as puppies.
2 are with families and 1 is with an older couple.
Æ