I'm curious to know which Kdramas have love triangles that a lot of fans actually loved instead of hate. Like where fans loved both of the ML and SML or FL and SFL instead of them just loving the SML/SFL that made them enjoy the love triangle.  Maybe the story was great that made the love triangle memorable to fans instead of being cliche/annoying 

Daily Dose of Sunshine: although I felt a little sorry for the SML, the ML was such a green flag!

Hometown Cha-Cha-Cha: I think both the ML and the SML are equally likable.

Thirty But Seventeen: the SML was funny but I didn't ship him with the FL. Also, the ML is just the cutest!

In both of these, I kept wishing that the 2ML would walk away - if anything was going to happen, it would have already. More painful to watch than enjoyable.

Fated To Love You

Warm & Cozy

definitely While You Were Sleeping (2017) ! both MLs were mature and lovable characters. although I slightly preferred the 2ML, I was still happy that ML and FL were endgame

I really liked the love triangle in The King in Love (mostly because the endgame was what I wanted).