All Korean dramas have the same plot.
A (guy) and B (girl) are the main protagonists.
C (guy) and D (girl) are the main antagonists.
A love B. At the same time, D loves A and C loves B. Somehow it ends up with A dying from disease (usually leukemia) or A coming back from United States, or A and B turn out to be brother and sister that got switched when they were young. Or D went on her own way after the story or C got killed.
They are always similar, unlike Hong Kong dramas or Japanese drama.
So I don't think I have a favorite one, but some of the songs are pretty good. ^.^