There are a lot of japanese visual novels, so it really depends on what you want exactly. Do you want the traditional schoool setting, harem, fantasy. Do you want more story driven or more sex oriented ones. I know some titles that are widely regarded as the best story driven ones:
Muv- Luv - Well thought out Sci-fi story. I would recommend googling the play order if you choose to play this one, it has a lot of games.
Majikoi - Everyday school setting with a martial arts/fighting theme. A positive would be a great number of girls to choose from.
Dies irae - A little bit gory/combat focused. Personally I hated it because of the MC´s personality but if you´re into majestic battles it can be good.
Devil on G string - Everyday school setting with some interesting twists. On the scale of visual novels the characters have great complexity.
Kara no Shojo - Absolute recommend if you like detective stories.
Saya no uta - Really dark story, kind of hard to say anything about it without spoiling it. You could categorize it as a psychological horror.
Except Majikoi and Kara no Shojo all of these are completely story driven games, and don´t have that great of a number of h-scenes, even Majikoi is 50-50. There is a really large number of japanese games that focus on the sexual aspect so without you listing any kinks that you want and more importantly what you don´t want it´s really hard to recommend any game of that kind.