1) Wrestlemania 31 (2015) : WWE United States Championship (reign #4)
Undoubtedly, this was Cena's best run as a champion in his WWE career. He carried the US championship with pride and elevated it into something really big. His open challenges were outstanding and produced some world-class matches, giving exposure to some of the best-untapped talents in the WWE. Calling this a great run would be an understatement.
To summarize this reign, Cena won his 4th United States championship from Rusev at Wrestlemania 31. He issued open challenges on Monday Night RAW, producing some outstanding matches with the likes of Kevin Owens, Sami Zayn, Cesaro and Neville. At Summerslam 2015, he lost it to Seth Rollins in a winner-takes-all match due to an interference from John Stewart.