I'm right there with a lot of the other posters...
"Secret Garden" - Holiday party kiss. omo...*Swoons* It was just so darn perfect and passionate, and had that emotional reaction of "FINALLY!!" because it means he's accepted her as she is. Ah, I watched that scene too many times to count. XD
Second would have to be..."Queen In-Hyun's Man" While I love the "tip-toe kiss" my favorite is actually right before that one, where he grabs her by her face and just dives in. *swoons* It just looks so wonderfully passionate and masculine that I saw stars. lol <3