Why pick between either album - Kid A or Amnesiac - when you can have both?
I used to think OK Computer was my favorite Radiohead album, but then I got high once and listened to Kid A with decent headphones and I felt the album in ways I hadn't before, so that gave Kid A the boost needed to dethrone it.
And then you can't really have Amnesiac without Kid A, can you? So yeah, have both!