I used to do Ed Parker,Ive allways liked the concept behind it,that when you start you need to defend yourself,so its all hard shots,then as you progress it moves over to Kung Fu with the idea that at this point you should be able to defend by redirection
I also like that except for the basic precepts,its very fluid,so teachers have the leeway to provide a more unique experience,rather then being stuck in a dogmatic,rote and note situation