It's going to depend on your tastes. If you like Love From Another Star because of Ji-Hyun then she's just as funny playing someone new to the human world as she was playing the neurotic starlet.
I personally preferred Goblin because I liked the music, visual settings and heavier feel to the show. It's a darker, heavier show and then there's humor whereas I feel that Legend of the Blue Sea is lighter and more humorous and goes darker for periods of time. It's the opposite sides of the same coin.
So for me I put Goblin above Love From Another Star and I put Legend of the Blue Sea below both of them. But it's not a large gap between the three.