Male/female is a tossup really. In my limited experience males are more engaging and likely to be more goofy with trusted people. Females, bit more focused and aloof. But that is anecdotal at best.
Aggressive? Uh, that's another aspect that manifests later in the dog's life cycle. Some will argue nature vs. nurture on that aspect. I've run across VERY few truly aggressive dogs in my many years. It's a really bad trait for a pack animal, survival chances are wicked low for an aggressive animal. You could possibly mean drive, and that is channeled aggression, if you will. GSDs are known to be able to direct that energy into productive venues.
Offleash-I hope you mean walkies without a lead, not a dog with no boundaries. I can't do the no lead thing, it worries me too much. I have too much love/blood/tears equity in my dogs to even chance a dash into the road. On lead at all times when out of the fenced in area.
Never cook bacon while naked.