Any manhua based on the novels Mo Xiang Tong Xiu written, it has all the elements I enjoy.
BL itself
mo dao zu shi & blood bank
just to be clear, blood bank can look as though it's just a kinky manga but oh boy does the story and characters and fucking plot twists blow minds.
I second that and suggest you start with mo dao zu shi
After i read this answer, I immediately read the question again HAHAHAH
Never understand/Out of control Manhwa, Man my favourite one
If I say "masterpiece" what is the first BL that comes to your mind??