not sure but, if we're talking about classics, maybe junjou romantica (idk any manga before this)? but it doesn't really get attention here. back when i first started reading yaoi, ten count was the most popular for me. it will even have am anime adaptation this coming 2020. killing stalking, bj alex, and a guy like you are one the top list too, if we're talking about popularity. they are also still receiving a lot of attention even if they are completed.
still iconic series though lol. it's gonna be part of the OVA '6 lovers', along with Seitokaichou ni Chuukoku, Ze, Ameiro Paradox , Ten Count, and
Renai Ruby no Tadashii Furikata. though i'm not sure how they're gonna fit it in a single OVA if ever lol. maybe we're gonna get more than one, i hope. (๑•ㅂ•)و✧
Japanese Mangas Only
Here's a more objective view:
Before 2000: Zetsuai
2005: Gravitation
2008: Junjou Romantica
2010: Seven Days
2014: Ten Count
2015: Finder
2016: Twittering Birds Never Fly
2019: Dakaretai Otoko 1-i ni Odosarete Imasu
Most popular overall: Junjou Romantica
Best popularity growth: Kuroneko Kareshi
Current most popular: Dakaretai Otoko 1-i ni Odosarete Imasu
Rising star: Given
Tentative Korean Manhwa list:
Before 2000: Let Dai
2005: Totally Captivated
2016: Killing Stalking
Love is an illusion and if u hate me so we’re really really popular. Junjou romantica and sekaiichi hatsukoi are amazing, they’re definitely really popular. I know ten count was huge. Killing stalking is everywhere, if it’s yaoi lots of of people think to killing stalking. Finder is an older yaoi, it has lots of chapters and it has lots of djs. Really big hit there too. Love stage even had an anime, it was really popular.
Everyone please tell me. According to your experience, what's the top most popular BL manga/hwa/hua. Doesn't have to be what's popular now, but definitely been popular before.