Jesus Christ talk about an impossible decision. I love them all for different reasons and Amnesiac and Kid A are so damn close, but I'd have to say Amnesiac. That said, the previously unreleased/B-side of most of the Amnesiac songs are my favorite versions of those songs such as Like Spinning Plates (live) and an earlier version of Motion Picture Soundtrack. Ahhhhh! Yes. Kid A would be my choice.