Most Bittersweet Moment - The Shield's final run and Kurt Angle's retirement (Tie)
Since 2013, whether as a collective or as individuals, members of The Shield were atop the WWE. During the brand split, Dean Ambrose was a major player on SmackDown while Seth Rollins and Roman Reigns were among the top guys on Raw. They were three of the biggest stars in the company and industry.
Any time they reunited, it was saved for a special occasion. They had all gone off on their own and won titles. But once it was revealed that Ambrose would be departing, WWE set off on a farewell tour for the trio.
They fought together on RAW several times and had a final PPV match together at Fastlane before 'Mania. They even had The Shield's Final Chapter special on the WWE Network. But once all was said and done, the trio would be no more with Ambrose leaving the company.
Just as bittersweet (but also necessary) was the retirement of Kurt Angle. Long known as a strong technical worker, it was becoming apparent that he had lost some of the pep in his step. Because of that, he had his farewell tour and final match at WrestleMania 35.
While it was sad to see him complete the in-ring portion of his career, it was certainly time. He couldn't perform like he had been even five years ago.
You always want to go out on top but sometimes your body just tells you it's time. Even though pro wrestlers may want to keep going into their 50s, they really shouldn't if they have trouble sustaining a match of more than five minutes.