Some people think male greys are more aggressive until you talk with someone who owns a territorial female. Both sexes learn to talk; both sexes might not talk. One sex does not talk earlier than the other. Both sexes are as intelligent as human toddlers, needing lots of stimulation and activities. Both sexes require good nutrition and clean cages.This is another question I have had about grey's (not sure if I should start a new thread on this), you talk above about differences between males and females. Do people prefer one over the other? If so if there any factual difference in temperament between the two?
Both Congo and Timneh African greys have the intellectual capacity of a 5-year-old child and the emotional level of a perpetual 2 year old. Timneh African greys are known to have a more stable personality than their larger cousins, because they have a faster maturation rate. Congo’s can be just as stable with the right encouragement, commitment and nurturing. Sociability varies from bird to bird. Generally speaking, both subspecies are cautious birds. African greys have a tendency to sit back and observe the environment before becoming an active part of it.
Aggression is absolutely something you can modify. I think a male may just be "bolder" than a female...not necessarily aggressive. They are quicker to approach while hens may tend more towards "follow the leader". Of course, I'm just speaking of tendencies, not about individual birds because that will vary greatly.
Greys have a "monkey see, monkey do" tendency. Your grey will probably copy some of what you do. This will be very subtle and you may not notice it, but greys study EVERY THING and one day you will see the evidence of it.
These animals are seriously clever and really do pick up on negativity and if you feel negative about a bird liking you well don’t be surprised if your bird doesn’t pick up on that fact, and lets just say, not be your best friend.
So personally, in my opinion, it doesn't matter with male or female in regards to aggression.