#1 Brand Split

Separating the brands, giving SmackDown Live legitimate standing instead of disqualifying it as the 'sister show' to Raw and establishing separate Titles for each show have been some of the best changes effectuated by the WWE in recent history.
It's garnered more television time for Superstars, given them more kayfabe purpose to exist with myriad Titles to contend for and also provided us, the fans, with two pay-per-views a month to look forward to.
WWE's huge mistake with John Cena revealed - Watch Here!
The WWE mucked up the previous brand split but it would seem, for all intents and purposes, that they've rectified their mistakes this time around.
SmackDown Live comes across as a separate entity by itself, thanks to the feel-good factor surrounding it by having Daniel Bryan and Shane McMahon at the helm, and has thus far proven to be a breeding ground for talent that wouldn't have been as successful on Raw.
Pause a second to spare it a thought.
Jinder Mahal as WWE Champion and Shinsuke Nakamura as the challenger: It's a scenario that you would be hard-pressed to even dream up just a year back.
And yet, here we stand.