Her marriage to Khal Drogo and how that strengthens her as a character, how she deals with his death, and how she realizes her true destiny makes Daenerys my favorite character in all of Game of Thrones. I really can't wait to see her and her three baby dragons go in and wreck the treacherous Lannisters! Although, Tyrion's cool. He's the only Lannister who isn't a total prick, and even then he is; he's just awesome (my second favorite character in the whole show actually).
Still, a strong, smart, beautiful woman with three dragons at her command that has the blood of a Dragon herself is pretty epic. I wish the whole story were simply about her!
That and Emilia Clarke is gorgeous!