No matter how much I love Megas XLR its pretty obvious that Gurren Lagann would easily win against Megas. Maybe if Coop actually knew what he was doing instead of pressing random buttons and eating fast food then it might be a more of an even fight = P
Voting in favor of Gurren Lagann. While both the mecha pilots are impulsive and reckless, Kamina and Simon actually know what actions they are doing with Gurren Lagann while Coop's just button-mashing his way to victory.
Gurren Lagann should win. Megas does have quite the capability for mass destruction however Coop barely knows what he is doing and randomly presses buttons and mostly wins due to random bursts of extreme luck.