I cannot agree that Ender's Game, Hyperion and 1984 deserve to be there.
Have to agree with 1984 not deserving to be there, it was important to bring that particular subject to the public consciousness. But others wrote on the some subject and did it better. I've never been impressed with Orwell's writing style.
On the up side of the list, can't argue with the novel in the number one position for 20th century science fiction, Dune (imho) is the single best SF novel ever written.