Although I ride both, the Wave Witch is the ultimate SUP buster. Gets into waves earlier with an easier paddle back out. I use it mostly on windy days where the SUP would be just above frustrating. The Witch is basically half Surfski, half surf kayak, and Very Fast. Check it out:
http://www.youtube.com/watch?v=ov9Azm0rzuM&feature=c4-overview&list=UUzc36LG0Dcntbazs8SgTADw