I would say the game favors making the avatar male, if only because of the whole "children bound to the mother" thing.
Or think of it like the Hindus/Muslims/Chinese would: you're getting rid of one woman that you have to get married off, and turning her into a man that you can marry off (because you have to get all the pre-Say'ri girls married, whereas the males, nominally, have a choice). With Male Avatar, you open up more backend characters to marriage (not counting the bonus paralogues, Basilio is the sole late-game male, versus Say'ri, Tiki, and Flavia), and you can have another couple (along with whomever Chrom marries) that has two children, and so you have to do less work at getting all the children and can create a more intricately bonded setup.
Monster Hunter: pissing me off since 2010.
