I really dislike the "MC is the only male to get sex"-trope. Basically, I'd love to see more poly-relationships and less classical harems. In particular in incest games, there should be more than one male and all family members should be open to sex with eachother (eventually). I'd also like to see stuff like MC sharing his girlfriend with her father (or his grandfather), or MC helping his best friend to score with friend's mom.
If the game delivers on pregnancy, I would appreciate some input on who gets pregnant by whom, as I'm likely to have strong opinions on that.