Aik din aap yoon, from Yes Boss has been one of my choices for the longest time.
So has teri odh from Singh is Kingh.
One of my friends used the song, "Aik larki ko dekha to aisa laga," from 1942 A Love Story. And it was unbelievable, how WELL that song worked! The instrumental part in the beginning of the song is perfect as the audience awaits your entrance.....and the words of the song should begin......Exactly WHEN YOU ENTER!
You have to time it right. It's not a song that I would have ever chosen, but she pulled it off beautifully.