The Strikes Back death is a classic, forever will be. It was notorious a scene for Pokémon back in the day by firmly establishing that, powerful as Pokémon are, they still share the world with some force that one could reasonably call magic. Interesting to note, Pokémon's very own Junichi Masuda doesn't look at the corresponding "redo" death in the I Choose You movie any favourably in comparison, calling it and most scenes in that movie kinda "flat attempts to reference the original". Honestly, I feel the same way about the whole movie as a concept.
Temple of the Sea is one death I would have not minded if it had stuck its landing actually: he dies by his own hand and by no (direct) intervention of a Pokémon, and mirroring M8 he does so while performing an actual heroic sacrifice of the kind we would expect Ash to do. Instead, what do we get? He gets revived by a "Vicitni preview", given friggin' Super Saiyan powers including the glowin golden hair, and completes the movie.
Fortunately the movie can be pushed under the rug in that it gave way to an actual multi-movie plotline with the Creation Trilogy (M10, M11 and M12) where Ash managed to do more out of his own personal qualities rather than by using Pokémon do to the job for him.
Curiously enough, a trilogy where despite the power brackets involved Ash did not die. Helps that starting with M11 Giratina basically owes him a bit of a life debt.