Sullivan had a good left? Not according to Corbett. Faster than Dempsey? I doubt this. Sullvian's build to me is not the type that has quick feet. The concept defense or lateral mobility was not described in any news clip I read on Sullivan. The tale of the tape between the two is pretty close here. Dempsey is taller and longer. Sullivan might have 10 pounds of weight. Without a doubt, Dempsey beat better competition. One can argue who hit harder. Somehow, I think you might change your pick if you research Dempsey for a book.