Viewfinder. It just kind of defines the genre while broadening it at the same time, includes the tropes without being ruled by them. A traditional yaoi structure with a semely seme and a ukey uke but who are also interesting individuals with depth of character.
http://www.mangago.zone/read-manga/you_re_my_loveprize_in_viewfinder/
"Complex" has always been my all time favorite yaoi manga that always makes me ball my eyes out at the end. It's not everyone's cup of tea because Tatsuya cheats on Jun with a women and gets her pregnant but I thought that was important to the story overall. Also ignore the first chapter, that normally gets people to drop it!! (●'◡'●)ノ
Totally Captivated. The art is beautiful, The story is really really great. This manhwa make me laughing, crying, blushing and gigling from time to time. It stir my emotion so much. I was totally captivated over and over again. Even there's no hot sex scene but it's give you those butterflies feeling in your stomach. This one was a few manga out there that didn't annoy me to death. You know when you read a great story then you got annoyed at the lead that you drop it.
Well for me: (all of them has different type of seme and uke making them stand out from more and make story more interesting)
Koisuru boukun
Ten count
Hua hua you long(sp?)
Kuroneko series
1 of my all time fav! http://www.mangago.zone/read-manga/complex_manda_ringo/
But No.1 yaoi manga was, is & always will be "ZE" (▰˘◡˘▰)
Forever this one ---> http://www.mangago.zone/read-manga/vassalord/
Why? Because...plot & hot

In your mind, what's your number 1 yaoi manga?