Most Impressive: Vader reveals the truth to Luke – he didn’t kill Anakin. He is Anakin! [in The Empire Strikes Back].
Why The Force Is Strong With This One:The moment on which the original trilogy hinges and, without which, there would be no prequels. But mainly it's #1 because standing on a catwalk, dangling over a massive chasm, is an amazing place to deliver a bombshell.