When I think of doujin otome games I've tried, top of the list is definitely the game Second Reproduction. Former members of Heterodoxy who made this game then created a commercial game company called Operetta, and anyone who plays R18 otome games probably know of their game Koezaru wa Akai Hana(which is made by their R18 division Operetta Due).
I remember being so surprised with Second Reproduction due to how defined the MC was, because even in the late 2000's, MCs in otome games still tend to be blank slate protagonists. Not to mention that the MC was fully voiced(I think. I don't remember if it's partial or full), which is like, so rare at that time period.
Even in Koezaru wa Akai Hana, the MC there also has a prominent character. However, it seems like even Operetta Due has stopped making new titles, which is such a shame.