For me it'll be "Sharin no Kuni, Himawari no Shoujo".
Not only is it set in a small village in a present-day dystopian society, it also shows the importance of "freedom" and "individuality", things we mostly take granted, that are not in totalitarian countries.
Geh, enough of this crap.
What I try to say is, that it combines political/social topics like "freedom", "individuality", "society" with personal e.g. "love", "friends", family", "career", "duty", "future" etc.
It tries to make the reader question the world he/she currently lives in.
Sometimes I believe it is more philosophical than it should be, in a good way of course.
But it is not an all-gloomy story at all, because, as almost all VNs, it features comedy during the routes.
The main character is easy to relate to and most importantly not dumb.
There are 3 main heroines, which are all stereotypical VN-girls:
First is shy, long-haired, coodere, a slight airhead and basically the quiet type. (Normal chest)
Second has a ponytaily, is deredere and the energetic-but-lazy-when-it-comes-to-work type. (Big chest)
Third is short-haired, good-willed, tsundere with a big mouth. (Yes, she IS flat-chested)
There also is a fourth, secret heroine, which I won't talk about as of now, don't want to spoil the fun.
Also, there are five endings, each of these has some kind of epilogue, which tells you what happened to the main character and your heroine a few years after the main story ends.
H-Scenes are fairly normal. Nothing worth discussing. No rape, NTR or anything like that.
In the end "Sharin no Kuni, Himawari no Shoujo" is a very beautiful VN, which tells us a dramatic story set in a society where people are oppressed by the government every day.