1) The E3 2013 KH3 reveal trailer?
2) The D23 2013 gameplay reveal trailer (First Attraction Flow reveal and Mount Olympus confirmed as a world)?
3) The E3 2014 short teaser trailer (Young Xehanort talking with Young Eraqus)?
4) The E3 2015 trailer (New Attraction Flows and Keyblade Transformations, alongside Rapunzel's world reveal)?
5) The Jump Festa 2016 trailer (The return of the Yellow Opera and Pink Agaricus Heartless)?
6) The 2017 Orchestra trailer (more than 2 party members and lots of other new stuff)?
7) The D23 2017 trailer (Toy Story world reveal trailer, many more new features and, finally, a RELEASE DATE)?
Mine is number 7.