shotokan has some of the best(if not the best) katas in martial arts. kyokushin is great for sparring and fighting. you will not go wrong by choosing one of them or even both if you can.
http://youtube.com/watch?v=qLmA9r0M8Do
http://youtube.com/watch?v=Cz16G9-PERM
http://youtube.com/watch?v=oNtGF1-1ZYs
http://youtube.com/watch?v=d8pNSS4lPuY