Hmmm, never really thought about this... It's a bit hard because there are a lot of dramas I adore in which I love one of the characters much more than the other, so my favorite dramas don't always correspond to my favorite couples... In fact some dramas I rated horribly have my favorite couples :/
Let's see...
1. Kang Tae Joo & Han Eun Soo (Que Sera, Sera)
2. Jang Hye Sung & Park Soo Ha (I Hear Your Voice)
3. Feng Teng & Shan Shan (Boss & Me)
4. Chen Momo & Zhuang Jun Nan (ToGetHer)
5. Kim Mi Young & Lee Gun (Fated To Love You)
6. Domyoji Tsukasa & Makino Tsukushi (Hana Yori Dango)
7. Kang Woo & Han Myung Wol (Myung Wol The Spy)
8. No Eun Seol & Cha Ji Heon (Protect The Boss)
9. Toyama Sakura & Saeki Hiroto (Last Cinderella)
10. Do Min Joon & Chun Song Yi (You Who Came From The Stars)