If you have an adult female who has been an “only” cat for some time, it is best to get a younger female. Males, even friendly ones, can over-power and frighten females. Male kittens, while more easily dominated by the female, still grow up to be rambunctious teenagers that engage in a style of play that involves pounce and wrestle (not a older female’s idea of fun).
If a young, active male is your family pet, he would really enjoy having a male buddy who shares his enthusiasm for vigorous play.
A laid-back, older (neutered) male cat may enjoy “mothering” a kitten–male or female. They usually make better mother substitutes than spayed females. Females, in general, are less accepting of newcomers.
Males tend to bond with each other unless both have dominant personalities.
A dominant cat engages in a lot of rubbing–scent marking–behavior, likes to rest in high places (for surveillance purposes) and in doorways (to control the entrance to certain rooms), and shows little or no fear.