Hmmm, hard to say:
Great Dane coz I love my height advantage;
Labrador coz they're loyal like me;
Bullmastiff/Rottweiler mix coz no one messes with them;
German Shepherd or Groendael coz they're awesome (and fluffy)
or a wolf hybrid coz wolves are epic!
I think I'll go with Great Dane/Labrador mix!