[Britster]

Dobermans have major same sex aggression. Males cannot live with other males, in general, and no reputable breeder will sell a male Doberman to a household with another male. Dobermans require A LOT of exercise, stimulation and socialization.

I don't know a whole lot about Great Danes but most I've met seem to be "gentle giants" and most don't require a ton of exercise (but I could be wrong about this). A lot of happy to lounge around the couch. It can tricky with them as puppies because you are really not supposed to run them for 2 years while their joints and bones grow. Running around a backyard is fine, but you can't over-do the "forced" walking or running, etc.

I hope to have a large breed again someday. Particularly a German Shepherd is my dream. But Border Collies (though they are definitely not as huge, on the smaller side of 'big') have interested me lately.

To be honest, Jackson requires more exercise and attention than the Rottweiler that I watch, LOL. He's pretty high maintenance.

I'd love to have a GSD when I live alone or move out. I must say, I feel very safe walking around with a Rottie.