I tend to prefer 3DCG visual novels with good storylines, attractive, personable love interests preferably with small breasts, long gameplay, and not too many sexual kinks. I'm okay with the sex scenes being vanilla, and those being in the back seat rather than the focus of the game. Genre-wise, I like a lot of different settings as long as there's a romantic element woven in, and the MC doesn't treat his girls badly. I can't stand MC's who are constantly calling their LI's degrading names just for the sake of appearing dominant.
Also, I much, much prefer to play games that have already been completed.