What breed of dog should we get as a companion to our aggressive dog?

Our dog is a German Short-haired Pointer/Cadahula mix. She is spade & weighs approx 75 lbs. She loves to play with our neighbor's lab but she plays aggressively and is definitely the alpha dog. What kind of dog would be a good compliment to her? It is important that the breed not be inherent to digging, definitely no labs! Thank you for your recommendation!