I think I'd have to go with the final moments from "The Muppets Celebrate Jim Henson". Not just the reading of several letters, which absolutely tugs at the heartstrings, but what puts me over the edge every time is during "Just One Person", when Kermit comes into the picture. It's the most profound right upon his entrance, in my opinion, because he's not speaking, he's just watching all the rest of them. Maybe it evokes for me an image of Jim's ghost, silently grinning and watching the scene and appreciating all these people. Then, when Kermit finally speaks and says "See, I knew you guys could do the tribute for Jim", we hear the "new" Kermit, and are even more moved to know that, in some way, part of Jim will never die.
Just my two cents!