For me, it came down to Mark Henry's speech and attack of John Cena, and Brock's sudden appearance and attack of CM Punk.
Mark Henry coming out of his usual heel persona and giving a heartfelt speech about retiring from a business he's loved for close to twenty years, only to turn it around and put Cena down on the mat and throw the title on top of him is easily gonna be a memorable Raw moment (certainly one of the best of 2013 thus far) for years to come.
But seeing Paul Heyman's top two guys, who have never met on-screen before, stare at each other without saying a word before they physically interact for the first time ever with Lesnar F-5ing Punk (followed up by Brock smiling and laughing) was great, too.
I voted Henry but it was close.