I like Venus Flytraps because it's a plant so weird no one would believe it exists if it were not already so well-known and documented.
If Venus Flytraps became extinct and some future teacher told his or her students about it, they probably wouldn't believe such a plant ever existed. But then they would see all the great photos of Venus Flytraps from the past and really regret that such an amazing plant was ever allowed to become extinct.
I like birds, epecially parrots since I was raised in the rainforest of Peru where we regularly saw big Scarlet Macaws flying in groups across the sky. I wish I could see the one and only parrot native to the United States, the Carolina Parakeet. But it has been extinct now for almost a century.