the first thing i recommend people when they ask for good yaoi manga is KASHIKOMARIMASHITA DESTINY. Its an Omegaverse manga but it has really really good plot! With about 10 plus chapters.
Second would be, if youre a fan of yakuza theme - Finder and Kobi no kyoujin, and also Saezuru tori wa habatakanai,
comedy /cute/ fluffy- Honto yajuu, itoshi no nekokke
Some other long ones that i love; Hidoku shinaide, Sekaiichi Hatsukoi, Punch Up, Koisuru Boukun
Thank you (●'◡'●)ﾉ
http://www.mangago.zone/home/mangalist/25771/
I specially recommend "Yuuutsu Na Asa" & "Zankoku Na Kami Ga Shihai Suru" from there. But brace yourself before reading them as both of them delves deep into you psyche & pushes it to it's limit.
Genwaku no Kyoudo (I think I spelled it right lol)
This is one of my faves and definitely deserves a read If you haven't already.
http://www.mangago.zone/read-manga/komatta_toki_ni_wa_hoshi_ni_kike/
one of me favourite shounen ai uwu it's a bit old, and has a "old time manga" vibe XD because of the way they are drawn. But it's rly cute!!
Any suggestions for a manga (shounen ai or yaoi) with a GOOD plot and preferably a long one ?