I vote Booker because he embraced the ridiculousness of the gimmick. I mean, a grown-ass man walking around with a crown on is pretty fukked up. Booker took the comedy to a high level, and that's the way it should be with a King gimmick.
Lawler's made a lot of money with it, though, I'll give him that. And the Macho Man had a great run. Still, Book was the most entertaining King.