I mostly read M/F. For me, when I first found out about my interest and started to look for stories online, I much preferred more historical themes, such as naughty English schoolgirls being sent to the headmaster/mistress, or ladies in Victorian or medieval times getting a spanking from their (future) husbands. Because, as I used to reason, CP was normal back then and people didn't know any better. Women being expected to follow a man's lead was normal back then. I had trouble enjoying stories set in modern times because it felt wrong to do so. Being born in the 80s, in the Netherlands, as a woman you're supposed to be a man's equal.
It took more exploring to realise that being a bottom or submissive in a relationship doesn't mean you're somehow below your husband, nor does it mean that his decision is final in every aspect of life. So, nowadays I do enjoy M/F set in modern times, as long as it's clear the dynamic follows from the choices the couple made, what works for them, and not from either the author of the male character in the story being a misogynist pig who feels entitled to authority for the sole reason of having been born with a penis. Somehow that doesn't bother me as much when it's historical fiction, but in modern times, just no.
I enjoy F/F too, but I'm less into the mother or aunt spanking a younger family member thing. Not that I entirely avoid those stories, but I mostly read those from authors I consider to be very good writers, because I know I'll enjoy the story even though the dynamic doesn't excite me.
As for F/M and M/M, I do enjoy such stories and have written a few, but it's not the idea of spanking a man I find exciting. I like to pretend I'm a witness, or I'm the man on the recieving end
