I prefer love, but it depends from the type of game really. love route shouldn't be without darkness either, but in a darker setting with blackmail etc the horniness sits better. it's hard to justify the family basically getting raped AND falling in love. not impossible, and would give great complexity to characters if you can pull it off, but unlikely that any of us can write well enough.
then again, the way the horny setting gets ruined in 99% of the games is having the women jump on the dick with zero effort. mom sees son's big dick, and bam instantly wants to fuck him. no story, the mom isn't going through anything emotionally to get where she allows herself to fuck the son. with love route there tends to be at least somekinda romantic plot before you get to the action, however cliche. a bad story is still a story.
either way you decide to go, there should be 1) reluctance, and 2) getting over the reluctance should be a story with a beginning, a middle and an ending. doesn't have to be the war and peace, but it should be a story. otherwise when the women give in there is no payoff. the size of the payoff is directly related to the size of obstacles to win before getting there.
the milfy city mom for example is how you do horny wrong. you can't stop the mom from fucking you, and it just ruins everything. one of the hottest moms ever wasted. the caroline story is already tons better. she loves you all the way, but you still have to work for winning her over. which also shows the mom/sister doesn't have to hate the mc to have an arc.
a shitty personality doesn't make the heroine a bigger challenge, it makes you want her less. which is the opposite of what we're trying to do here. we want her to be the most desirable, yet the most unattainable. that's the golden rule of incest games. that's why mc's mom is better than your friend's mom. the mountain to climb is bigger.
the way the big brother mom blueballs you is just perfect. you really need to work on her for more than a year before she gives in, and even then she hides her interest for a long time. along the way we hear from her sister how the mom is secretly turned on by the events, but she's fairly cold doing stuff to you until she makes the emotional breakthrough in the end. with all its flaws, I think this is the main reason why big brother is so popular.
