Lv1 Yuusha ga Megami Jashin to ♀ Monster Hanshoku Keikaku Hajimemashita! is Aomidori's Monster Girl game. I enjoyed it, but it's not really mainstream due to the masochism scenes. It does have lamia and a centaur in it though!
Vanadis VNs are probably the easiest to recommend, although the Japanese in them is highly conversational. On the bright side, the vocabulary is simple, but on the downside, textbook Japanese and/or machine translators aren't going to take you far.