When I was a kid, I assumed that coke was the stronger brand. In retrospect, that impression was probably created by the "Pepsi challenge" marketing plan when I was kid (this was the 1970s).
But flash forward to the last 10 years and you wind up with a tie game between the performance of both stocks. Pepsi was the winner during the previous expansion. The two had similar performance in '08, Coke eventually outperformed Pepsi from 11-13, but now the two are more or less tied.