This isn’t even a debate.
He returned to WWE in 2012 and has worked 61 matches since then, according to CageMatch.net. That includes house shows. The fact that he makes the kind of money he does while working a schedule like that is enough alone to award him the honor of this completely meaningless award.
Of those 61 matches, he won 48 and lost just 12, two of which were the Royal Rumble. A title was on the line in 31 of those matches, and he won 24 of them. He even won a Money in the Bank match!
He has headlined WrestleMania twice since his return. Oh, and there’s also that other thing he did at WrestleMania back in 2014: he broke Undertaker’s streak.
Beyond all this, Lesnar is one of the very few actually unique performers on the WWE roster. Much of the roster will give you the same basic concept in each match, so much so that even the good matches feel routine. And while Lesnar matches later in the decade became a bit too formulaic, his freakish size and athleticism make him stand out at all times.
Lesnar is just different, and WWE would have been much worse off without him over this past decade.