In general, male cats are more territorial and less sociable than females. So female cats are less territorial than males, which answers the question. In addition, males generally have larger territories (home ranges) than females. This might mean that they encounter other cats more commonly than females which might also mean that they have more opportunity to be aggressive towards other cats. Territorial aggression can be directed towards dogs and people as well.
The fact that female cats are less territorial than males might be a factor when adopting a new cat into a household in which there are existing cats.
In multi-cat households there will be, at least potentially, territorial issues. When more than one cat lives in a home they have to become more sociable and accept the presence of other cats in close proximity. They find harmony most often it seems to me but sometimes one or two cats can be permanently stressed. If females are more sociable and less territorial than males then the natural conclusion would be that they could be more accepting of other cats in multi-cat households.
Another element in this scenario is that stress can play a role in idiopathic cystitis. This disease is less common in female cats than in males. The conventional explanation by veterinarians is that the tube leading out of the bladder, the urethra, is normally narrower in males and therefore more likely to be blocked causing cystitis.
Dr Bradshaw suggests that as female cats are less territorial and more sociable it may be that they are less stressed because they are more able to resolve or avoid conflicts in e.g. multi-cat households. This is just a thought because I know sometimes cat owners struggle with ensuring that a new cat fits into, with the least possible stress and problems, a new household in which there are already existing cats.