Not manhua or manhwa (I read very few of those to begin with), but I did drop some stories because of the MC's personality.
Usually because they were acting too stupid, consistently making the obviously wrong choices as if on purpose, let everyone walk over them for no reason, or were otherwise insuferable.
1. A weak protagonist who only wallows in their emotions instead of taking action, who repeats the same mistakes over and over again.
Reminds me, that's why I stopped watching Tokyo Ghoul. People told me it gets better, but when I saw the MC whining and crying more often than not (I'm not joking, it really was
at least half of the time I saw him on screen) through the first
three episodes, I just could not continue. I already skimmed through the latter two of those episodes, because I just could not stand him.