I stumbled across the Einstein vs Hawking one when I was searching for something else a few months ago, and thought it was kinda good. Saw "Mr .T vs Mr. Rogers" in the related videos, laughed at my childhood, and then continued watching them. They're pretty good, and I'm always looking forward to more. I thought the recent Bruce Lee vs Clint Eastwood was really good. Other decent ones include Leonidas vs Master Chief, Sinatra vs Freddy Mercury, and pretty much all of the female battles.