Even though I've only seen the Act II pas de deux (on one of the Nina Aniashvili videos), the Giselle who really sticks in my mind is Rose Gad of the Royal Danish Ballet - I believe she was dancing with Alexander Kolpin?
Katrina
I think I'd have to go for the closing tableau of Les Noces, with all the heads resting on top of one another. It's just such a powerful and distinctive image.
Katrina