Kakashi's is better, since it does what its supposed to. Chidori and Raikiri are supposed to be assassination techniques, but chidori was incomplete because it sounds like 1000 birds chirping - not exactly stealthy. Raikiri is a more concerntrated and doesn't make noise, hence why it is considered a better technique.
The argument that Sasuke's variants are better isn't really that strong since Kakashi also has variants like the running beast and lightning chains.