I think he was given the title on the strenght of his dominance in the major competitions within the genre...I believe he's won more "Calypso Monarch" titles than anyone else so the crown in indisputably his to wear.

In my mind though...I'm kinda partial to Kitch, not really sure why, I think he was just more creative than Sparrow. The thing about Kitch that probably escaped most people was the fact that he was an intellect...and had an obviously quick wit. Sparrow may have mastered the raunchy double-entendre, but Kitch was master of the understated.