FRS is more battle suited since it is controlled by the user till the last moment of execution and can be varied as per requirement...
Kirin is most probably a one-time matter since Sasuke would run dry after one use and despite being very fast, it still can be avoided... So, it doesn't serve it's purpose well...
But, as far as destruction goes, Kirin is more destructive where FRS being not a mass-destruction type still has much damage...