I honestly think that 2017 was worse.
Positives: Braun Strowman, Samoa Joe but got injured, Balor vs Styles, Owens headbutts Vince, AJ vs Lesnar, New Day vs Usos, The Bar and the four way at Summerslam
Negatives: Everything about Angle, Survivor Series, the bitched Shield return, the son of Angle angle, KO vs Styles, everything about SD, Dean Ambrose, the Universal Championship, Jinder Mahal

2015 wasn't bad, it just was more down to earth. Not many things were happening that really made an impact. Whereas in 2017 and 2016 so many things happened, wether they were good or bad.

It was just a good year.

If you wanna see what a bad year feels like, check out post Wrestlemania 2010 up until MITB 2011. Those 15 months must have been the worst months in WWE's post AE history. Nexus, Kane vs Taker, Swagger, Sheamus, R-Truth, Cena vs Batista, Bret as US champ, The Corre, Del Rio, the misbook of Punk, Bryan at WM 27, the entire WM 27, Michael Cole... Damn