Growing up, we briefly had a rhodesian ridgeback/black lab mutt (black rhodesian? labraridge?)... it was one of the NASTIEST dogs I have ever met, and (unfortunately) after it started attacking us kids, we had to take it to the vet...
At which point we got the most beautiful, most friendly and best behaved dog: a golden retriever/collie mutt (golden collie?).

Now that our daughter is old enough to help with the care, we're looking for a dog, and it will likely be a mutt, just because. :)