#2 John Cena vs. Seth Rollins — WWE SummerSlam 2015
By 2015, John Cena had achieved something no one expected. He made the WWE United States Championship relevant again. Cena's reign with the United States title was one of the best things he did throughout his career.
At SummerSlam 2015, however, he came face to face with Seth Rollins. Both men put their titles on the line. Whoever walked out was going to walk out as a double champion.
If Cena won the match, he would be a 16-time WWE Champion. Unfortunately, thanks to interference from Jon Stewart, Cena was unable to win the title at that time.
Stewart was apparently a Ric Flair fan and felt it was wrong that anyone should tie The Nature Boy's massive achievement. John Cena was in incredible form as he put Rollins over in the match, making him seem an even bigger threat.
This came at a time when Rollins was yet to be established as a proper top name. A win over Cena, and their feud, helped build him up in the eyes of the audience. Since then, Rollins has remained a top name for WWE.