I also don't like male leads that are mean/cruel to the female leads. I almost never watch those at all.
But even among the male leads who aren't mean to the female leads, most that I came across aren't really 'kind on the outside'/nice and kind type. Either they are arrogant/jerk-ish in the funny way, or they are normal (not sweet/kind). Which is ok by me as long as they treat the girl well.
But if you want the kind ones, maybe check out 'Doctors'. The guy is definitely sweet on the female lead, and his personality is on the nice/kind side.
If you don't specifically want kind/nice personality, just that he is nice to the female lead, check out 'Sound of the Desert' (Chinese historical romance). He is never ever ever mean to the female lead. Best male lead in my drama watching history.