Usually I'm an equal-opportunity player, which means I like equal representation of all genders and races if possible. However for D3 I've been creating characters based on what seems to be their canonical sex (i.e. the one which has been dominant in their promotional videos etc - I'll probably go for the opposite gender if I ever play them in Hardcore) which means I'll be going for a Male Crusader and only have female DH and Wizard.
Besides, the geneseed process only works in males.