Which one was better?  Those are both a couple of my favorite dramas, but I liked While You Were Sleeping more.

I hear Your Voice. The story and the acting was  better. 

I loved both but "I Hear Your Voice" is the best.

I hear your voice

I love while you were sleeping more, although gotta admit that I hear your voice had a solid plot.
If you are asking story wise I hear your voice one of the best i have ever seen.

While you were sleeping had great story but not up to the level of i hear your voice.

Well if i had to choose , i would choose , while you were sleeping.... I just love this one, i have no idea how much times i have rewatched it.

 Serena:

While You Were Sleeping  ... I thing just the first episode was masterpiece 

it sure is....

 Serena:

 For me first episode was awesome and have a nice end but after this episode everything became so bored

well, i respect your opinion. Everyone sees every story in different perspective.
there are dramas i just love, but when i showed my friends, they didn't like it at all. Vise verse is also true though.