I want to state for the record that I am NOT anti-monster girl. I'm just very particular about the kinds of monster girl manga that I like.
A CENTAUR'S LIFE (Sentoru no Nayami), by Kei Murayama. First published in 2011 and first published in North America in 2013.
PLOT:
In a world populated with all sorts of half-human races lives Himeno the centaur girl. She lives out her days with her centaur family, as well as her draconoid friend Nozomi and goat-like friend Kyoko. Together they live out their everyday lives as they deal with the challenges of a world that must make accommodations for all the various races, be it racism against Antarctic snake people, the ethics of riding a centaur, or coming to terms with non-human genitalia.