5. Batista
Other than the fact that Cena dropped the title to Batista on the Road to Wrestlemania after putting Sheamus over. Dropping the title to Batista majorly put him over as a heel. Batista would then did some of the best work of his career with the, “I’m better than you because you’re too busy kissing babies and hugging fat girls” shtick.
Two years before that at Summerslam 2008, Cena and Batista squared off in singles competition for the first time. Cena lost that match clean to Batista and put him over huge. It was the better for who was the best and at the time, it was Batista. Shortly after that, Cena has surgery and Batista was World Heavyweight Champion two months later.