Probably the revelation that Hillary finally admitted it was her fault Trump is President. Now there can be peace in politics... after we go over the 10 worst e-mails in the "Not Russian" DNC Hack.
Most of the opposition research on Bernie has leaked out, but I think the most damning thing would have been watching him have to try and give actual answers to questions. In a primary you can just focus on 1 issue, but as the nominee you have to give answers eventually, and Bernie was pretty bad outside of economics. Trump was a fucking moron*, but at least he tried to have answers that the lowest common denominator could understand, and all he had to do was continually lie and confirm peoples deepest most unfounded fears about Hillary. With Bernie, it would have been impossible to know if he was lying or not, and some of the stuff he wasn't lying about would have seemed pretty outlandish. He could have just made up so much shit about Bernie being a communist and people wouldn't really be able to tell it wasn't true.
* - Trademarked by Rex Tillerson