#3 CM Punk

CM Punk tried and tried, but it was always a no for the WrestleMania main event.
CM Punk instantly became WWE's hottest star in 2011 after his viral shoot-promo on RAW in July of that year. Punk became WWE Champion at Money in The Bank, but wouldn't see the main event picture that often on Pay-Per-View, thanks to being overshadowed by John Cena most of the time.
There was no chance of Punk main eventing WrestleMania 28 thanks to the dream John Cena vs. The Rock match, but Punk had his eyes set on WrestleMania 29 in 2013. He was still WWE Championship at the beginning of the year and looked to be possibly heading that way.
Unfortunately, Vince McMahon saw dollar signs in a Rock vs. Cena rematch, and that would serve as the main event once again.
Punk has since said that he tried to convince WWE officials on having the match as a Triple Threat, also involving him, but they were not interested. Looking at how Rock vs. Cena II came out, Punk's inclusion probably would have been for the better.
Becky Lynch has been challenged HERE.