I prefer the webtoon. Its much more realistic. There is no way any girl would stay single because her bf has left and keep on simping for years, moreover love fades with time, if the couple does not stay together. No matter what they say, it is never the same once one of the people leaves.
I am a Seojun fan. So for me, webtoon has given much more to his character than just Jugyeong's one sided lover and Suho's once-upon-a-time best friend. He and Jk got together and later seperated because of his career (idols need to be single). Not like the drama where he never got together and chose to be in painful love), it also hinted a new beginning for Seojun with another girl.
The webtoon did not have much to Soojin's character though. So the only good thing in the drama than Hwang In Yeop is Kang Soojin.