I think Jordan's cocking-it-back from the foul line was more of a classic than Kemp's.
The other one I've always liked was Carter in 2000 with the windmill that was almost in reverse to the rotation of his body.
Tough to find new ideas after all this time. The sticker on the backboard, bouncing it off the back/side of the backboard (Iguodala?), the candle, etc are all fairly fresh. I'd hate to be anyone tasked with coming up with something new this year.
It's also tough to practice any stunt dunks reliant on a big jump and accuracy - more you're doing it, the more exhausted you get. (Not speaking from experience!)