I know it's very sappy and corny, so I apologize in advance...and I'm usually not a fan of stories where everything in wrapped up into a nice little bow at the end...but to me those scenes in the final episode starting with Vic (great addition to the show for me), and all of the scenes where the characters are thinking back and we see brief clips from past episodes, and finally the camera pulling away from DS9 slowly with Kira and Jake in the window, and that music! They successfully pulled at my heart on that one. It was an awesome finale.
(sorry, I know those are multiple moments and not a single moment. I cheated.)
My only wish, and I know others have mentioned this, is for Worf's "looking back" scene to focus on his relationship with Jadzia rather than Ezri, or at least MOSTLY scenes with Jadzia. I understand that there were reasons behind the scenes. But it would be nice for that to be corrected if we ever get DS9 on blu-ray. It shouldn't be too difficult and hopefully enough time has passed that they can do it.