I've never owned a dog as I prefer cats, but my buddy has a Rotty crossed with a Black Lab, and it si the nicest dog ever. It has the body of the Lab, but the head, and colors of a Rotty, with the tail on still. Massive dog and stand as tall as me, 6'3, when standing on his back legs.

Coolest dog though. He'll run around with you for hours, or sit and chill on your lap and sleep. He's not mean, but he protects his territory when unknown people come around.

But I really do like the Black Labs. Very smart dogs, loyal, and not the biggest dogs on the planet either. They're easy to train and are used most common in seeing eye dogs.