If Yamato’s transformation can make her fly, this seems a really good chance to show it. Luffy about to hit the water, nobody to save him, them bam, dramatic doublespread of transformed Yamato who shows up and saves him.
But I think it should be Momo. This is a great time for him to overcome his fear of flying/heights, his inability to control his powers and his sense of uselessness compared to everyone else. Plus, he’s the one with seemingly the best CoO on the island who has been “hearing” what has been happening. He should be aware that Luffy’s voice is falling.